Honestly I would see how long each of the phones have been water damaged for and choose the one that’s been water damaged fro the least amount of time. Reason being is the longer the phone has been damaged the more messed up it will be.
I would try opening up the phone and look for any corrosion. If there is corrosion that is most likely the problem. If their is no corrosion then I would do a full reset and see if it’s a software issue. Best of luck
I would think it would be the camera that went bad again. Try and replace the camera and if that doesn’t work something is wrong with the board. I could also be a software problem. Try doing a full restore and hopefully that works.