Vita slim D-pad/rhumbstick ghosting?

[GravityLoL]

I recently bought myself PS Vita Slim but as soon as i booted it up, i noticed that it keeps scrolling up on it's own.

I dissasembled it and cleaned up both D-pad and thumbstick but problem seems to be still present, as it keeps scrolling up no matter what i do.

From what i've noticed, either of thumbsticks doesn't work at all but i didn't booted up any game so i can't tell if they should work in home screen at all

What could be at fault? Should i try replacing d-pad and thumbstick or maybe try to replace whole left part of the board?

any way i can pinpoint what is exactly a problem?

EDIT:

Ok, i think i managed to slightly pinpoint the problem, which i say it may be either stick or touchscreen being faulty

After downloading few homebrew platformers, it looks like it's not problem with d-pad , this one seems to work fine.

Sadly, i encountered another problem. Suddenly, my Vita turned off.
I managed to check out it with VItaSident and battery health was listed as " 99%"
It doesn't seem to charge up either , since indicator doesn't seem to glow and it doesn't want to boot up either now and it was charging after purchase, since i charged it up to full

EDIT 2:
I managed to get it back to living somehow, looks like connecting with a battery was loose . I ordered new one, just in case

So, back to square one:
It's probably a screen that's giving me an issue. Otherwise, it's all good .
Is it easy to fix?
Currently, i'm a little scared to disassemble it further, not gonna lie