ASUS RT-AX53U boot issue

Installing and Using OpenWrt
1

Hello,

I had installed stable 23.05.x about a year ago on the ASUS RT-AX53U and it was booting fine.
Since it has been powered off and was stored away.
Now I wanted to utilize it again, but it did not boot up (power LED stays on without blinking when switching power on.
So today I thought, I am going to open the case, solder a PIN header for serial access and check what is going on:

When booting, it gets stuck about a second in:

U-Boot SPL 2018.09 (Sep 08 2021 - 14:31:58 +0800)
Trying to boot from NAND

Initializing NMBM ...
Signature found at block 1023 [0x07fe0000]
First info table with writecount 0 found in block 960
Reading from 0x1e0000, size 0x100000
Succeeded

RT-AX53U bootloader version: 1.0.0.1
Reading from 0x1e0000, size 0x100000
Succeeded
MAC Address: XXX
Reading from 0x1e0000, size 0x40000
Succeeded
Check Factory's EEPROM successfully! (r = 16)
Reading from 0x2e0000, size 0x40000
Succeeded
Check Factory2's EEPROM successfully! (r = 16)
Reading from 0x3e0000, size 0x2000
Succeeded
Reading from 0x3e0000, size 0x7216a7
Succeeded
   Image Name:   MIPS OpenWrt Linux-6.6.86
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    7476839 Bytes = 7.1 MiB
   Load Address: 80001000
   Entry Point:  80001000
   Verifying Checksum ... OK
## Booting kernel from Legacy Image at 83000000 ...
   Image Name:   MIPS OpenWrt Linux-6.6.86
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    7476839 Bytes = 7.1 MiB
   Load Address: 80001000
   Entry Point:  80001000
   Verifying Checksum ... OK
   Uncompressing Kernel Image ... OK
[    0.000000] Linux version 6.6.86 (builder@buildhost) (mipsel-openwrt-linux-musl-gcc (OpenWrt GCC 13.3.0 r28597-0425664679) 13.3.0, GNU ld (GNU Binutils) 2.42) #0 SMP Sun Apr 13 16:38:32 2025
[    0.000000] SoC Type: MediaTek MT7621 ver:1 eco:4
[    0.000000] printk: bootconsole [early0] enabled
[    0.000000] CPU0 revision is: 0001992f (MIPS 1004Kc)
[    0.000000] MIPS: machine is ASUS RT-AX53U
[    0.000000] Initrd not found or empty - disabling initrd
[    0.000000] VPE topology {2,2} total 4
[    0.000000] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.000000] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000000000000-0x000000000fffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000000000-0x000000000fffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x000000000fffffff]
[    0.000000] percpu: Embedded 12 pages/cpu s19136 r8192 d21824 u49152
[    0.000000] Kernel command line: console=ttyS0,115200
[    0.000000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
[    0.000000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes, linear)
[    0.000000] Writing ErrCtl register=00008000
[    0.000000] Readback ErrCtl register=00008000
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 64960
[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[    0.000000] Memory: 243720K/262144K available (8369K kernel code, 651K rwdata, 1020K rodata, 5372K init, 229K bss, 18424K reserved, 0K cma-reserved)
[    0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000]  Tracing variant of Tasks RCU enabled.
[    0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[    0.000000] NR_IRQS: 256
[    0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[    0.000000] clocksource: GIC: mask: 0xffffffffffffffff max_cycles: 0xcaf478abb4, max_idle_ns: 440795247997 ns
[    0.000004] sched_clock: 64 bits at 880MHz, resolution 1ns, wraps every 4398046511103ns
[    0.008072] Calibrating delay loop... 586.13 BogoMIPS (lpj=2930688)
[    0.066226] pid_max: default: 32768 minimum: 301
[    0.079659] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[    0.086899] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[    0.103542] RCU Tasks Trace: Setting shift to 2 and lim to 1 rcu_task_cb_adjust=1 rcu_task_cpu_ids=4.
[    0.113374] rcu: Hierarchical SRCU implementation.
[    0.118073] rcu:     Max phase no-delay instances is 1000.
[    0.124130] smp: Bringing up secondary CPUs ...
[    0.129514] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.129542] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.129557] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.129607] CPU1 revision is: 0001992f (MIPS 1004Kc)
[    0.183586] Synchronize counters for CPU 1: done.
[    0.216165] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.216188] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.216200] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.216230] CPU2 revision is: 0001992f (MIPS 1004Kc)
[    0.275140] Synchronize counters for CPU 2: done.
[    0.305838] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.305860] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.305873] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.305908] CPU3 revision is: 0001992f (MIPS 1004Kc)
[    0.360339] Synchronize counters for CPU 3: done.
[    0.390203] smp: Brought up 1 node, 4 CPUs
[    0.401165] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.410978] futex hash table entries: 1024 (order: 3, 32768 bytes, linear)
[    0.421802] pinctrl core: initialized pinctrl subsystem
[    0.429953] NET: Registered PF_NETLINK/PF_ROUTE protocol family
[    0.436622] thermal_sys: Registered thermal governor 'step_wise'
[    0.438376] /pinctrl: Fixed dependency cycle(s) with /pinctrl/pinctrl0
[    0.466553] clocksource: Switched to clocksource GIC
[    0.481767] NET: Registered PF_INET protocol family
[    0.486916] IP idents hash table entries: 4096 (order: 3, 32768 bytes, linear)
[    0.495914] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 4096 bytes, linear)
[    0.504230] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear)
[    0.511902] TCP established hash table entries: 2048 (order: 1, 8192 bytes, linear)
[    0.519528] TCP bind hash table entries: 2048 (order: 3, 32768 bytes, linear)
[    0.526737] TCP: Hash tables configured (established 2048 bind 2048)
[    0.533999] MPTCP token hash table entries: 256 (order: 0, 4096 bytes, linear)
[    0.541521] UDP hash table entries: 256 (order: 1, 8192 bytes, linear)
[    0.548007] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)
[    0.555849] NET: Registered PF_UNIX/PF_LOCAL protocol family
[    0.561526] PCI: CLS 0 bytes, default 32
[    0.568925] workingset: timestamp_bits=14 max_order=16 bucket_order=2
[    0.577398] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    0.583167] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[    0.603424] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 251)
[    1.054059] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    1.060304] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    1.066261] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    1.072523] mt7621-pci 1e140000.pcie: host bridge /pcie@1e140000 ranges:
[    1.079222] mt7621-pci 1e140000.pcie:   No bus range found for /pcie@1e140000, using [bus 00-ff]
[    1.088024] mt7621-pci 1e140000.pcie:      MEM 0x0060000000..0x006fffffff -> 0x0060000000
[    1.096155] mt7621-pci 1e140000.pcie:       IO 0x001e160000..0x001e16ffff -> 0x0000000000

(log from last boot, but previous ones, got stuck at the same message)

Then I thought to reinstall via tftp and followed the instructions on the device page.
I tried both openwrt-24.10.1-ramips-mt7621-asus_rt-ax53u-squashfs-factory.bin and openwrt-24.10.1-ramips-mt7621-asus_rt-ax53u-initramfs-kernel.bin
Both showed the two error lines as in below log at the end and both stopped booting at the same stage as the log above.

Using eth@1e100000 device
TFTP from server 192.168.1.2; our IP address is 192.168.1.1
Filename 'openwrt-24.10.1-ramips-mt7621-asus_rt-ax53u-initramfs-kernel.bin'.
Load address: 0x83000000
Loading: T #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #################################################################
         #######################################################
         2.5 MiB/s
done
Bytes transferred = 7476903 (7216a7 hex)

*** Loaded 7476903 (0x7216a7) bytes at 0x83000000 ***


Erasing from 0x3e0000 to 0xb1ffff, size 0x740000 ... OK
Writting from 0x83000000 to 0x3e0000, size 0x7216a7 ... OK

*** Firmware upgrade completed! ***

Error: no Image found at offset 0x003e0000
Error: no Image found at offset 0x003e0040

Does anyone have any idea, what else I could try, or is the flash dead?

2

Use asus recovery tool, and never ever "install" initramfs again. Instructions are there for a reason

3

Sure, but the device already got stuck at the same stage, even before installing anything.
And as said it did work correctly before I had put it to the box.

4

As far as it shows you flashed OpenWrt in a completely incoherent way.
Get back to OEM FW

Then install according to instructions (no tftp or uboot tricks involved)

5

I might have flashed the wrong one when trying to revive it, but I had correctly flashed it initially with 22.03 and later had upgraded it to 23.05 (I believe 23.05.2)!
Something must have broken during the power off (at least a year).

Regarding the Asus tool, I need to get a Windows booted (really sad, when there are always just tools for Windows), so it needs to wait until the weekend.

Then we will see, if the flash is broken or factory image is able to fix it again.

6

Yhat upgrade enabled 2nd soc mii connected to wan port and you lost wan connection, now you are doing more damage.
It is very simple to install

7

You can try tftpboot-ing the kernel with initramfs, then sysupgrading USING SYSUPGRADE FILE not keeping config.

8

Not sure, what your problem is and why you need to be that salty?

You might refer to my old post from more than a year ago? That might be a combination of a non standard "LAN" cable in the building, where other OpenWrt devices were able to flawlessly negotiate 100 Mbit/s, but this device had issues with it (23.05.0 Update breaks WAN - RT-AX53U/1800U - #45 by fireburner). As a matter of fact, I actually wanted to upgrade to 24.10 and see if it behaves any different with that cable.
This had nothing to do, with me installing OpenWrt the wrong way in the past!

Also as I said before, the device was broken and did not boot any more, before I flashed the infamously initramfs while trying to revive it. So something must have altered since it was last booted.
But instead you assume I am complete idiot, just because I did one mistake and that you therefore won't trust any of my other statements any more.

9

Might be electric damage from the fancy cable.

10

Where should this magical energy come from, if there are two standard network devices on each end?
Nevertheless, I tried to tftpboot the initramfs.bin openwrt-24.10.1-ramips-mt7621-asus_rt-ax53u-initramfs-kernel.bin but it stopped at the same kernel message:

[    1.048014] mt7621-pci 1e140000.pcie: host bridge /pcie@1e140000 ranges:
[    1.054676] mt7621-pci 1e140000.pcie:   No bus range found for /pcie@1e140000, using [bus 00-ff]
[    1.063496] mt7621-pci 1e140000.pcie:      MEM 0x0060000000..0x006fffffff -> 0x0060000000
[    1.071659] mt7621-pci 1e140000.pcie:       IO 0x001e160000..0x001e16ffff -> 0x0000000000

Will try the Asus tool next, but I don't have much hope.

11

Unfortunately booting still fails after having used the Asus Tool

serial log while using the Asus recovery tool:

Image Name:   
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    43438886 Bytes = 41.4 MiB
   Load Address: 81001000
   Entry Point:  81001000
   Verifying Checksum ... OK
Erasing from 0x3e0000, size 0x296d366 ...
Succeeded
Writing to 0x3e0000, size 0x296d366
Succeeded
Erasing from 0x35e0000, size 0x296d366 ...
Succeeded
Writing to 0x35e0000, size 0x296d366
Succeeded
done. 43438950(0x0296d366) bytes written

boot log from first boot after using Asus tool:

U-Boot SPL 2018.09 (Sep 08 2021 - 14:31:58 +0800)
Trying to boot from NAND

Initializing NMBM ...
Signature found at block 1023 [0x07fe0000]
First info table with writecount 0 found in block 960
Reading from 0x1e0000, size 0x100000
Succeeded

RT-AX53U bootloader version: 1.0.0.1
Reading from 0x1e0000, size 0x100000
Succeeded
MAC Address: <XXX>
Reading from 0x1e0000, size 0x40000
Succeeded
Check Factory's EEPROM successfully! (r = 16)
Reading from 0x2e0000, size 0x40000
Succeeded
Check Factory2's EEPROM successfully! (r = 16)
Reading from 0x3e0000, size 0x2000
Succeeded
Reading from 0x3e0000, size 0x296d366
Succeeded
   Image Name:   
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    43438886 Bytes = 41.4 MiB
   Load Address: 81001000
   Entry Point:  81001000
   Verifying Checksum ... OK
## Loading kernel from FIT Image at 83000040 ...
   Using 'config@1' configuration
   Trying 'kernel@1' kernel subimage
     Description:  MIPS OpenWrt Linux-4.4.198
     Type:         Kernel Image
     Compression:  lzma compressed
     Data Start:   0x83000124
     Data Size:    3851648 Bytes = 3.7 MiB
     Architecture: MIPS
     OS:           Linux
     Load Address: 0x81001000
     Entry Point:  0x81001000
     Hash algo:    crc32
     Hash value:   bc434e23
     Hash algo:    sha1
     Hash value:   0ceeebde5dc660b7686ca7221e06a9d72d3d93c2
   Verifying Hash Integrity ... crc32+ sha1+ OK
## Loading fdt from FIT Image at 83000040 ...
   Using 'config@1' configuration
   Trying 'fdt@1' fdt subimage
     Description:  MIPS OpenWrt mt7621-rfb-ax-nmbm device tree blob
     Type:         Flat Device Tree
     Compression:  uncompressed
     Data Start:   0x833ac7e8
     Data Size:    11203 Bytes = 10.9 KiB
     Architecture: MIPS
     Hash algo:    crc32
     Hash value:   a60c718b
     Hash algo:    sha1
     Hash value:   7203d5d756400c621650318339f6e3d7f808cb3d
   Verifying Hash Integrity ... crc32+ sha1+ OK
   Booting using the fdt blob at 0x833ac7e8
   Uncompressing Kernel Image ... OK
   Loading Device Tree to 8fe67000, end 8fe6cbc2 ... OK
[    0.000000] Linux version 4.4.198 (gitserv_asus@tpbuildsvrvu01) (gcc version 5.4.0 (LEDE GCC 5.4.0 unknown) ) #1 SMP Wed Apr 30 12:22:26 CST 2025
[    0.000000] SoC Type: MediaTek MT7621 ver:1 eco:4
[    0.000000] bootconsole [early0] enabled
[    0.000000] CPU0 revision is: 0001992f (MIPS 1004Kc)
[    0.000000] MIPS: machine is MediaTek MT7621 RFB (802.11ax, NAND with NMBM)
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 10000000 @ 00000000 (usable)
[    0.000000] Initrd not found or empty - disabling initrd
[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000000000000-0x0000000000ffffff]
[    0.000000]   Normal   [mem 0x0000000001000000-0x000000000fffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000000000-0x000000000fffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x000000000fffffff]
[    0.000000] VPE topology {2,2} total 4
[    0.000000] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.000000] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.000000] PERCPU: Embedded 10 pages/cpu @81f53000 s9280 r8192 d23488 u40960
[    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 65024
[    0.000000] Kernel command line: console=ttyS0,115200 rootfstype=squashfs,jffs2
[    0.000000] PID hash table entries: 1024 (order: 0, 4096 bytes)
[    0.000000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
[    0.000000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
[    0.000000] Writing ErrCtl register=00008000
[    0.000000] Readback ErrCtl register=00008000
[    0.000000] Memory: 246076K/262144K available (7953K kernel code, 2955K rwdata, 2052K rodata, 276K init, 323K bss, 16068K reserved, 0K cma-reserved)
[    0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[    0.000000] Hierarchical RCU implementation.
[    0.000000] NR_IRQS:256
[    0.000000] clocksource: GIC: mask: 0xffffffffffffffff max_cycles: 0xcaf478abb4, max_idle_ns: 440795247997 ns
[    0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 4343773742 ns
[    0.000009] sched_clock: 32 bits at 440MHz, resolution 2ns, wraps every 4880645118ns
[    0.007773] Calibrating delay loop... 586.13 BogoMIPS (lpj=2930688)
[    0.070396] pid_max: default: 32768 minimum: 301
[    0.075105] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.081629] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    6.443079] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    6.443088] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    6.443098] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    6.443238] CPU1 revision is: 0001992f (MIPS 1004Kc)
[    0.177400] Synchronize counters for CPU 1: done.
[    6.220321] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    6.220327] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    6.220333] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    6.220401] CPU2 revision is: 0001992f (MIPS 1004Kc)
[    0.267731] Synchronize counters for CPU 2: done.
[    6.310419] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    6.310426] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    6.310432] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    6.310514] CPU3 revision is: 0001992f (MIPS 1004Kc)
[    0.352914] Synchronize counters for CPU 3: done.
[    0.357648] Brought up 4 CPUs
[    0.361201] devtmpfs: initialized
[    0.368987] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.378773] futex hash table entries: 1024 (order: 3, 32768 bytes)
[    0.385061] pinctrl core: initialized pinctrl subsystem
[    0.390853] NET: Registered protocol family 16
[    0.431276] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    0.436904] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    0.442536] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    0.448532] mt7621-pci 1e140000.pcie: Failed to get gpio for PCIe1
[    0.454671] mt7621-pci 1e140000.pcie: Failed to get gpio for PCIe2

edit: There might of course also be the option, that I had hardware borked it when soldering the serial pins onto the board. It was quite hard to reach enough temperature for a proper solder, because the board was draining the heat quite good.

12

Oops, thats really bsd luck.
Both kernels cannot be wrong about pcie though.

13

@fireburner I haven't followed along, but have you tried to flash the stock firmware with the Firmware Restoration Tool? I've read there are some issues with the latest stock 386_69104, so I would try the one before that 386_69086, or maybe even the one before that 386_69061. You can download them from here: https://www.asus.com/networking-iot-servers/wifi-routers/asus-wifi-routers/rt-ax53u/helpdesk_bios?model2Name=RT-AX53U

*Note: make sure to unpack the zip file before the rescue procedure. BTW, are you carrying out the procedure correctly? It can get tricky.

14

Thanks for the info. I will try an earlier stock firmware.
From the serial logs you can see, that the firmware restoration tool hat correctly flashed the firmware.