Bricked Archer C6U v1.0

[Marcin_Pl]

Hello,

By accident I uploaded 22.03 build on one of my TP-Link Archer C6U v 1.0.
It resulted in the boot loop. Could anyone suggest what steps to take to restore the original firmware?

So far I tried:

1. start Web Recovery using both reset and WPS button, but with no luck.
2. tftp serwer from both 192.168.0.66 and 192.128.1.66 connect to LAN1 and WAN port, directly and through the switch, but no single log appeared.

Any advice would be appreciated. Thank you.

The boot loop looks like:

1. Power led turns on green for 4-5 seconds
2. Power led turns off for half a second
3. All LEDs turn on green
4. after a second WAN led gets orange and turns off immediately
5. all process repeats

Best regards,
Marcin

[brada4]

What did you upload to router?

[GWTechTalk]

Most routers don't have a serial connector by the time they make it into the hands of the consumer. The sure fire way to fix it is to get a serial connector to USB cable then direct wipe and flash the operating system. That's if you can find the storage config ISO from the manufacture or if their firmware is properly formatted to be direct flashed. Most are.

Enterprise routers have a serial connection by default for this exact purpose.

[Marcin_Pl]

Hi,
By accident I uploaded OpenWrt 23.05.01 version and most likely this has happened:

TP Link Archer C6U new Flash Chip (WINBOND 25Q128JVSQ is now XMC XM25QH128C)

TLDR: Archer C6U has new flash, FW image from device page does not include spi-max-frequency patch. successfull build new image with: openwrt/imagebuilder:ramips-mt7621-23.05.4 flashing new Archer C6Us with <=23.05.03 might result in a soft bricked device caught in a boot loop. device page has this version linked. My First Post, be gentle We stumbled upon a new hardware version of the Archer C6U. The Version is not depicted anywhere on the outside, nor the PCB.…

Best regards,
Marcin

[brada4]

@brada4

What did you upload to router?

You need to hold some button to prime up tftp at start.
Check routers boot with wiresharl om 1st and last lan ports. Noisy windows highly unfit for the task.

[Marcin_Pl]

Hi,

I managed to debrick Archer C6u v1 from the boot loop.
Any combination of the buttons does not work (as I wrote already in the initial post). I had to connect via serial port to start Web Recovery.

After opening the case you will see here the serial ports:

I marked the ports that you need to connect to. Please note that RXD pin on your cable goes to TXD on the board and TXD from your cable goes to RXD on the board. GND to GND. Fourth one stays empty.

Then check with the Device Manager which COM is your serial.

In my case it is COM5

Then Open Putty and choose Serial connection and set the options to:

After that open connection.

You shall see the console, showing progress of booting the device.

At certain moment you see failure of the file system mount and router reboots.

During the boot you have an opportunity to interrupt the boot process:
Press 'x' to enter recovery web server
and when you do it it shall end up like this:

Then on 192.168.0.1 you will find the rescue web that will let you to upload original firmware

After uploading and rebooting you should see the login page.

I could not login (admin or empty password did not work) but after factory reset it was fine.

I hope this will help other ones having similar problem.

Best regards,
Marcin