Yesterday, My GS3 began randomly shutting off. I would check my phone and it would be turned off. I called Sprint and they told me to go to the sprint store and get it looked at. A couple hours later, now it shut off, I tried to turn it on and it won't power on past the Samsung screen. It will constantly vibrate and try to start, but it usually will not actually start. If it does come on, it will go off after a minute or two and start this cycle again. I am not rooted. ANybody else had this issue?