Yes - uninstall the Blessn900 and other device that use the camera such as the Flashlight.

Reboot, and if it runs, its the lens cover sensor curse.

Install the applications you removed, one at a time. Put it simple, you may have flipped the cover back by accident and back causing the sensor to act as a semaphore/lock. The other applications leave it to the Camera to be "master" of this. A variant this is the quest for "who let go of that smell" - where the first one to respond is assigned the responsibility.