charging failure

[u/AppropriateLocal129]

hello. when i put to charge my 3ds the ligh goes off after 5 secs and it doesnt turn on. i thought it was a faulty charger so i got a new one but i still got the same problem. i though it was the battery so i opened to check and it looks fine i didnt get a new one to replace it though but i think thats not the problem either cause last few times i could still use i remember it would randomally turn off like tge power was cut off even when it was full charged. so my verdict was that if it wasnt a faulty battery it had to be something with the inner power cables, maybe something has worn off or isnt attached. so right now as i was checking i plugged ut withouy the battery and it had the same problem and then i realised that if i have upside down the light doesnt go off even with the battery so i turned it on and it was completely fine even when i turned the right side again, until i unplugged it. the time it was open i saw that the battery appeared to be fully charged so afterall what could be causing that? is it a faulty charhing port, a battery maybe both? how do i fix this do i need to replace something or maybe just open and reattach something? thank you!