I don't why it's doing that but I have had it happen before and every once in a while it still does it. By pressing and holding down the lock button, the home middle menu button, and the up volume button at the same time and then after you feel the first buzz/vibration let go of only the lock/power button to get to the emergency menu or whatever it is, although that doesn't always work for me either to reboot in safe mode. But it does work better if I plug my phone into the charger and let it sit a little while