TL-WPA8630P boot loop - serial cable?

Hi all,

I recently installed OpenWrt on my TL-WPA8630P but wanted to go back to the stock firmware. I flashed it back with sysupgrade but now it's in a boot loop. The symptoms are the same as in the following thread:

The user there was able to get a connection to the device using a serial cable. I've taken the back off the unit and can see the 4 holes in the PCB marked J1 which I believe is where I could make a connection.

Is there someone that could give me some instructions on how to make/buy an appropriate cable, and then how to connect to the unit (from Windows or Linux, I have both) in order to recover the device?

Thank you,

I've used this in the past

Thanks frollic, very interesting. I'll have to figure out which 4 of the 6 pins I need to connect to the powerline unit. Would the unit need to be plugged into the wall in order to use this or would the USB voltage be enough to get a connection when plugged into a PC/laptop?

No, you'll need the power.

And you only connect TX, RX, and GND to the device.

Given that the board I'm connecting to looks like this image, how would I determine which ones are TX, RX and GND?

Once I've got the hardware side of things sorted, what would the process be to connect and upload the firmware? I'm assuming Tftp will be needed but I've never used it before. I'm familiar with using Windows and Linux command lines, I could just do with a little guidance on the process - especially as it's currently in a boot-loop situation.

Once you've figured out which pins are what, you'll see the u-boot starting, and either force it to do a tftp recovery by holding down a button on the unit, or by interacting with the serial console.
If it works, TP-Link sometimes cripple the console

Assuming TFTP works, it'll tell you what IP you need to use, and what the name of the image needs to be.

For the v2, but could possibly also work on v1:

Ah, thanks tmomas - I saw that page previously but hadn't realised they may be the actual sequence of the pins/holes on the board. :+1:

I have some PCB pictures from months back i've been meaning to upload, including the serial pinout.

What steps did you follow? If they are from the wiki we need to make them safer, given how difficult it is to recover this unit...

Yeah, it was the steps from the wiki. The installation of OpenWrt worked fine but it just didn't do what I wanted in the end, hence my reason for wanting to go back to stock. I also followed those instructions from the wiki but you're right, the steps could be expanded to be safer. It would be good if they included steps on how to take a full backup first for those with the ability to dump the existing ROM to a file, or files, and how to safely restore afterwards.

Does this help?

Not quite, but thanks for the reply. I should have taken a backup of the ROM before flashing to OpenWrt which I would have done but couldn't find details on how to do that. My bad, I realize, but instructions on how to do that for this specific device might help others. As well as details on how to restore the backup should the need arise.