My rear iphone 5 camera stopped working!!!!

I just got my iphone 5 replaced due to a faulty lock button. I have had this phone for about 2-3 weeks and the camera worked for all that time. Then all of a sudden two days ago it stopped working when I went to go take a picture. It shows the camera screen and everything but it's just black. I checked and there's nothing blocking the camera. I tried doing a total restart and that did nothing. Restoring the phone did nothing. I'm totally fine with getting this phone replaced. AGAIN if I have to but id appreciate it if I didn't have to. Please help!!