wont charge but it should

This tablet is not charging.

-when i plug in charger it can comunicate with PC

-when i test it with multimeter it shows 4.35V connected to PC , 4.55V connected to WALL. ( on battery it says input : 4.35V)

-i tried to change battery and same thing

-when battery is charged , phone works but battery % are droping and than it turn off...when i try it with charger plugged inm than it is dropping even faster

-i tried to leave it charging for hours and nothing changed...

-sometims i can turn on tablet and it shows battery is charged to some %, but it starts to drop really fast again

-i tried hard reset

-charging port looks in perfect condition, and when multimeter shows it is ok i dont think if i replace it, anything will change

-of course i tried multiple cables

-when it is plugged in and i want to turn it on, it just show battery lvl for second and turn off... i need to plug it off to turn it on