Hi Huzaifa,
It's brilliant that you are trying to fix things! It's amazing how much longer things can be used with a bit of care and maintenance.
Yeah, the power bank sounds like a broken connection. Fixing it might be a bit trickier due to the case and it being closely packed, but it might work.
I'm happy to help with the soldering, just later (I've just come back to Taiwan and still in quarantine, and have to see how the Hackerspace itself is doing currently).
I haven't been to the Hackerspace for a while, so not sure what's the situation on the access, but weekend should be possible to be arranged. Don't know any *spaces in Hsinchu personally, it sounds like there should be something, since so much tech is made there.
Cheers, and keep in touch!
Greg