Samsung galaxy p5100

I have this Samsung galaxy p5100 which was not used for long time as something was wrong with it. So i decided to look and maybe to fix it.

1st day tryed to turn it on unsuccessfuly then plued in charging cable and noticed flickering screen with charging sign on and off. After removed a cable it went pich black and that was last time it showed some working signs.

2nd day i removed a cover and checked all conections if there are any loose and checked if it made any better unsuccessfuly.

3rd day i thought maybe battery is gone as itis old tablet replaced with new one same silance.

So i was wondering if you had similar issues and maybe have some ideas what i should try to do to bring it to the life.