PRS-T2 Battery dead/charging problem?

[yh.20]

Hello, I've been browsing this forum for the past few weeks trying to find a solution to my PRS-T2 issue, but so far all the possible solutions I've tried haven't worked.

The problem:
The device would run out of battery and, after being plugged in to charge (tried both wall charger and PC), would charge for a couple minutes then stop with the message on screen:

Power supply from computer through the USB cable is interrupted and cannot charge. Please charge the battery before starting up the device. It could take several minutes of charging before the device restarts.

The device has been in this cycle for a few days now,
-being out of charge
-charge for a few mins
-charging stops
-repeat


For additional clarity, I'll provide the history of this device and the repairs I've made.

History of device since I got it:
-Bought second hand early this year, the device appears to be well-used but still in working condition
-Plugged in to PC to sideload ebooks through Calibre
-The device would lose charge over a few days (from 100% to 0% in about 2-3 days)
-Eventually, I found that charges would not last as long, going from 2-3 days down to just sustaining one day of charge.

-I decided to do the soldering trick as shown in this video, but to no avail. The device could charge but will lose charge pretty quickly again.

-I ordered a new battery from AliExpress and installed it on the device
-The device could charge, but same problem - battery would only last a day on full charge

-As of a couple weeks ago, the device started having problems connecting to the PC, it would connect for a minute or two, then disconnect from the PC.
-Unplugging the cable and plugging it back did not change anything, the device wouldn't even charge from the cable.
-Restarting the device seemed to allow it to connect again, although I had to leave the device off for a couple minutes.
-Eventually, the device wouldn't even charge unless it completely ran out of battery.
-The leads us to the present problem as mentioned above.

I apologize for the lengthy post, but I want to be as detailed as possible so as to provide enough info about the problem should anyone who has a solution needs it.

To summarize, here are the steps I've tried to fix the device, to no avail:
-Bypassed the heat capacitor through soldering the ports on the battery
-Replaced the battery
-Soft resets
-Hard resets
-Tried charging through both PC and wall charger (though the wall charger isn't original but it does charge the reader)

I understand the device is old at this point, but I would love to have it working again as I know many still love and use theirs to this day.

Any help would be greatly appreciated!

[rkomar]

Have you tried using a different cable? It is not likely to be the problem, but then again, it is easy to check.

[yh.20]

Will try a different cable, though I've tried using several before, they've seemed to all work, but that was before all these problems surfaced.

Will update though, that I also tried leaving it plugged in in the "power supply from computer through USB is interrupted..." state for several hours, which didn't revive the device.

[yh.20]

Update: swapped the new battery back to the old one to see if the new battery was potentially broken, but the issue remains exactly the same – the device would charge for a few minutes, then the charging light would go out and the device would stop charging, popping up the same message.

Could it be that the issue lies somewhere else? e.g. firmware, USB port, etc.