TP-Linked Archer A7 v5.8 Bricked. No Keyboard on serial connection

Installing and Using OpenWrt
1

Hello All. So I have bricked my first router ever, a brand new TP-Link Archer A7 v5.8. I had the snapshot build of OpenWRT installed and working with LuCi, and then I just had to have a stable version, the install version. So I forced a downgrade to the install version listed for the router here:
openwrt.org/toh/hwdata/tp-link/tp-link_archer_a7_v5

Downloaded this: downloads.openwrt.org/snapshots/targets/ath79/generic/openwrt-ath79-generic-tplink_archer-a7-v5-squashfs-factory.bin

I forced the update and low and behold, a bricked router. My usb to serial converter arrived today, I set it up by soldering the 3.3v pads connected up to J1 and, BAM, serial text appeared on the screen.
What I do not have is the ability for keyboard input for some strange reason. I have on a Macbook Air, running Parallels with Windows 10. Under Win 10, I am using Putty and the proper drivers for the usb-serial device. Parallels asks which host I want to use for my USB device and I naturally choose the Win 10 host. AGAIN NO KEYBOARD INPUT is working into the router

Here is the dump of the serial interface out of the router:

U-Boot 1.1.4-g14abe3ec-dirty (Aug 10 2018 - 16:06:27)

ap152 - Dragonfly 1.0

DRAM:  128 MB
Top of RAM usable for U-Boot at: 88000000
Reserving 397k for U-Boot at: 87f9c000
Reserving 16448k for malloc() at: 86f8c000
Reserving 44 Bytes for Board Info at: 86f8bfd4
Reserving 36 Bytes for Global Data at: 86f8bfb0
Reserving 128k for boot params() at: 86f6bfb0
Stack Pointer at: 86f6bf98
Now running in RAM - U-Boot at: 87f9c000
Flash Manuf Id 0xef, DeviceId0 0x40, DeviceId1 0x18
flash size 16MB, sector count = 256
Flash: 16 MB
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   ath_gmac_enet_initialize...
No valid address in Flash. Using fixed address
ath_gmac_enet_initialize: reset mask:c02200
athr_mgmt_init ::done
Dragonfly  ----> S17 PHY *
athrs17_reg_init: complete
SGMII in forced mode
athr_gmac_sgmii_setup SGMII done
: cfg1 0x80000000 cfg2 0x7114
eth0: 00:03:7f:09:0b:ad
eth0 up
eth0
Setting 0x181162c0 to 0x50a02100
factory boot check integer ok.

factory boot load fs uboot len 131072 to addr 0x80010000.
Hit any key to stop autoboot:  0
## Starting application at 0x80010000 ...


U-Boot 1.1.4-g14abe3ec-dirty (Aug 10 2018 - 16:05:02)

ap152 - Dragonfly 1.0

DRAM:  128 MB
Top of RAM usable for U-Boot at: 88000000
Reserving 123k for U-Boot at: 87fe0000
Reserving 16448k for malloc() at: 86fd0000
Reserving 44 Bytes for Board Info at: 86fcffd4
Reserving 36 Bytes for Global Data at: 86fcffb0
Reserving 128k for boot params() at: 86faffb0
Stack Pointer at: 86faff98
Now running in RAM - U-Boot at: 87fe0000
Flash Manuf Id 0xef, DeviceId0 0x40, DeviceId1 0x18
flash size 16MB, sector count = 256
Flash: 16 MB
Using default environment

In:    serial
Out:   serial
Err:   serial
Net:   ath_gmac_enet_initialize...
No valid address in Flash. Using fixed address
ath_gmac_enet_initialize: reset mask:c02200
athr_mgmt_init ::done
Dragonfly  ----> S17 PHY *
athrs17_reg_init: complete
SGMII in forced mode
athr_gmac_sgmii_setup SGMII done
: cfg1 0x80000000 cfg2 0x7114
eth0: 00:03:7f:09:0b:ad
eth0 up
eth0
Setting 0x181162c0 to 0x50a02100
Hit any key to stop autoboot:  0
## Booting image at 9f040000 ...
Bad Magic Number
ath>

At "ath>" I cannot type anything, at "Hit any key to stop autoboot", I cannot type anything.
All pins are secure. Anyone run into this before?
I was using this video guides, can't post the links as I am only allowed 2 links.

2

fwiw, have you tried connecting RX and TX wires of your serial-TTL USB adapter together, and confirm whatever you type is echoed back to the screen, to verify the adapter is working correctly?

3

I have done this. I opened a putty to the same settings used to connect to to the TP-Link, connected Rx and Tx directly together, received input back to putty, disconnected the connection, no characters returned.

4

Do you mean you connected 4 wires? Including the Vcc one? Or just the 3 wires GND, RX and TX? Please note that sometimes you need to connect the TX and RX pins to RX and TX respectively so try changing the TX and RX pins and it may start working.

5

I only connect 3 wires as these guides instructed, TX, RX, GND:


I had also wired the Tx from serial to Rx on J1, and Rx from serial to Tx on J1.

6

You tried to sysupgrade with a factory image, thus bricked. It isn't necessary to force an upgrade of the same series of firmware (ath79 or ar71xx). Once OpenWrt is installed you can use C7v5 firmware including the 18.06.4 build under ar71xx.

Probably the easiest way to recover is with TFTP as described here:
https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=1e4ee63cc8d1889a78b539a5ed7be8d56e9b976f
This does not require a serial connection though you can use what you have now to observe the process.

Some models need a resistor or wire installed on the board to make a physical path from RX serial pin to the CPU. Also you may need to send 'tpl' instead of hitting any key. Try cutting 'tpl' to the PC clipboard then paste it to the terminal window when hit any key comes up.

3 Likes
7

Those TFTP instructions did it for me. Indeed holding the reset button launches the TFTP server, listening for host 192.168.0.66 and for file being hosted ArcherC7v5_tp_recovery.bin. Yes that says C7v5 not A7v5, but that is even what the bootloader is calling for as I could see what was going on with the serial connection. Thank you for your help and the link! I do have to say though, it will only take OpenWRT software, it would not take the stock firmware. It was calling out checksum errors when trying to flash the stock firmware

8

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