Camera causing iPhone issues

I cracked my screen a few weeks back and it finally died, it was completely black and would not respond at all. I took it to the repair shop who said there was a problem with the rear camera, getting too hot. They tried replacing the camera but it was still too hot so they have left it disconnected and replaced cracked screen. Also battery life is now half as good as it was before the repair. The only problem I had with the camera before screen died was the camera freezing after current update (only on photo, video was fine). Please help!