Weird battery?

I have a weird problem where my laptop can only be turned on two or three times before basically bricking. On top of that, when it boots, it boots up slower and slower. (First immediately on power button press, then only after holding it 5-10 seconds and then it bricks)

I need to open the laptop up, disconnect the battery and press the power button again for some time (discharge static)

I also usethe charger and do a few combinations of

-charger out / in

-battery out / in

While pressing the power button. It then turns on again once charger AND battery are back in. (Note that I really HAVE to do this plug out/in power button dance before it turns back on again (this is the weird one))

Either way, im 70% sure theres some weird startup problem with the battery, but there could be a problem with the power delivery on the motherboard....

Before I buy a new battery, maybe some of you might know a different diagnosis I didnt come up with or came across a similiar behaviour.

Btw. Its an ACER TravelMate X (TMX349 - G2 - 58W2) Windows