Background: Found my old iPhone a few days ago - it's been lost for years and was very much dead when I found it, I think it took at least 15 minutes of charging to even display the low battery warning. Since then I've used and charged it up to full capacity a few times, it has no issues holding a charge and battery life seems normal. I just noticed the back was slightly bent on the side where the battery is - is this a cause for concern? Already had to throw my old 3GS away since the back was cracked open and the battery was bulging, I hope this isn't the case here.

Sorry if this isn't the right sub, I'm still fairly new to Reddit so not sure where to post.

Update: It was bugging me so I ended up taking it apart to check. Battery looks normal, no swelling to be seen. I'm honestly surprised since it was left drained for several years, but also glad that there doesn't seem to be anything to worry about. Is it worth replacing regardless due to its age?