I recently dug out one of my old tablets because I wanted to use it again, but something must have fallen on it because there's a dent about 2-3 mm deep on the back metal casing of the tablet, kind of near the middle, definitely over the battery. Plus the battery was left completely drained for well over a year (or more, can't remember how long) which is also not great for it.

The tablet boots up and seems to still work okay, but now I'm kind of paranoid. How high is the risk that whatever dented the back of the tablet damaged the battery and now it's just waiting to catch on fire now that I've started using it and subjecting it to charge-discharge cycles? Should I also be worried about the deformed back case exerting pressure on the battery and damaging it over time as the tablet moves around? Are there any red flags I should look out for that something is not right with the battery?

Basically, can I just assume it's nothing more than cosmetic damage? Or is there a good chance that it will burn the house down?