My husband's phone started doing this thing a few days ago where it would shut off and come back on repeatedly. It was fine then till today. He got a fast boot message and it said the device is locked. Now it won't power on. No recent damage was done to it, so we aren't sure what caused this or how to fix it. Not sure what the most recent OS is on the phone. His phone isn't eligible for upgrade till next March. So the phone is less than 2 years old.