Iphone turning 8 off without charger

So, my Iphone keeps turning off (with full battery) when the charger is unplugged. When I turn it on without the charger, it will show the apple logo, and then it will turn it off. If I plug the charger in, it will turn on instantly and work.

Things I have tried: Hard reset and, deleting everything.

I have a strong feeling that the battery has plugged at some point where I dropped it, but I'm not an expert. hope you can help me.