This has happens to me also. Another thing to add to my lemon list. Here is exactly what happens.
I usually have my screen brightness set to minimum brightness. Oddly, when I go to click my camera icon, instead of going into camera, it makes my screen brighter for like 2 seconds, then it fails to enter camera mode, it then goes back to my regular dim setting, never even makes it into camera, just back to where I was, my home screen.
I restart my phone like 5 times, that usually finally fixes it. I don't know if this is hardware issues or software.
