iPhone restarts when plugged in

Trying to make repair iphones for friends/relatives as a hobby. Encountered this problem with an i7 Plus. Whenever it’s plugged in it will restart after a few minutes. Doesn’t matter if it’s connected to pc or outlet. Tried different cables and restoring in DFU was succesful. Can’t get in the device to test more like sound etc with headphones, because it’s icloud locked, and she would come tomorrow. Is this a charging IC problem? Device got dropped in the toilt btw lmao