This is what I do to fix this issue much of the time. I don't know why this sequence of events works but it does.
1. Take out the old camera. Do not test camera functionality until I say so. IMPORTANT
2. Now turn device back on and hard reset the device. Then Turn off.
3. Now put in the new camera. Turn the device back on.
4. Now do a hard reset again.
5. Once back on. NOW YOU CAN TEST THE CAMERA
'''Jonathan Hawkins'''
== RockIT Repairs ==
[http://rockitrepairs.com|Cell Phone Repair Shop]