Xiaomi R4A (v3.0.27) cannot debrick?

For Developers
6

What is the p/n of your 4A flash chip? How did you brick your routers, wrong openwrt fw?.

7

I haven't disassembled it yet so I don't know the correct versionof the flash chip. Is it possible to make a request via software?

Yes, I bricked the router obviously a wrong firmware at first. It was the latest version from https://openwrt.org/inbox/toh/xiaomi/xiaomi_mi_router_4a_gigabit_edition site.

8

Then, if you would not return the router back to seller, you have to open the case:

  1. check the flash IC, Eon EN25QX128A cannot use the official openwrt FW.
  2. connect out the serial port, and try to use TFTP software to debrick it.
9

If I understand well, it can't debrick normal way pressing reset button and powering on way? As far as I see the tftp works just firmware is not correct, see the following log line:
"dnsmasq-tftp: sent /tftpboot/test.bin to 192.168.31.11"

And the led light blinking purple very fast and nothing else happened. The router kept in bricked state.

I asked the official Xiaomi service helpdesk for correct firmware but they didn't help me unfortunately.

10

if you setup all tftp tools right, easy to debrick it in normal way.

But if something wrong, you cannot "see" it, so connect serial wires as a monitoring windows....

11

Thanks for advice, I don't have needed equipments for trying serial console access. I tried to examine the still working router and saw the following (accessing it via OpenWRTInvasion)

Very interesting, it contains a file named openwrt_release :slight_smile:

Look at these lines:

root@XiaoQiang:~# cat /etc/uboot_version
4.2.S.1

root@XiaoQiang:~# cat /etc/openwrt_release
DISTRIB_ID="OpenWrt"
DISTRIB_RELEASE="Attitude Adjustment"
DISTRIB_REVISION="unknown"
DISTRIB_CODENAME="attitude_adjustment"
DISTRIB_TARGET="ramips/mt7621"
DISTRIB_DESCRIPTION="OpenWrt Attitude Adjustment 12.09.1"
12

you still not confirm your flash IC p/n:

13

Thanks for your linked files, I tried them but it wasn't successful to debrick the router unfortunately. After it I opened the case of the router and made a photo. Please take a look at the picture, it seems for me it is an Eon chip on the board.

Have you any instructions how to connect to the router via serial console? But I am afraid of that it is a newer model which hasn' got support from xiaomi yet.

22-09-13 10-43-55 2482
22-09-13 10-43-55 24821920×1440 367 KB

14

EON chip, currently only above my code could be used to flash, OpenWrt official code will brick it.

Then you have to try serial connect + TFTP server or bootloader + TFTP server.

15

Thanks for the link, I donwloaded it, will try. Would you send me a bootloader image also to try to debrick it via tftp? Does it work with dnsmasq also or needed to use miwifirepair tool? (the second method needed Windows and I don't have it)

16

The bootloader is still there in the device, after you connected serial port, you will see and operate with the bootloader.

We do have both Linux and Windows PC.

17

Thanks, will try flash wwith your images sent before. May it use without debrick via tftp? Or needed to revert the original working operating system then flash it with yours?

18

For the not bricked good device, you could flash it as normal, using the acecilia/OpenWRTInvasion + Linux and using my code into the OS1.

19

Hi, flashing the router with your image successfuly done. Thank you! You make my day! :slight_smile:

20

Then, any new firmware to upgrade, you have to know the image must be patched for EON chip, otherwise it'll brick your router.

So you have to fix your debrick process asap.

21

Sure, you have right! But I don't have any idea without connect it via serial console. Have you any guidance how to make it, what additional devices needed to it? Thank you for any advice in advance!

22

I did use TinyPXE, need Windows PC, refer to:
https://www.youtube.com/watch?v=MWJCMukZWzo

Maybe Xiaomi factory tools also work.

23

Unfortunaltely any of methods above not worked for me. (tinyxpe, miwifi tool, dnsmasq as tftp all falled back to bricked state - I think any of used firmwares were wrong) I tried to keep in failsafe mode the good working router - but after 6 sec it booting forward in normal way. Is it possible to enforce keeping failsafe mode any way? (I tried with reset button pressing via boot)

24

Then you have to find the right way by yourself, and UART-to-USB tools is must, even Flash chip programmer/reader.

Because of your flash IC is EON, maybe you need a right factory image to do the unbrick. The normal images downloaded from internet, maybe not work with the chip, likes openwrt.

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