It seems my thunderbolt isn't charging correctly. It's not the charger but it seems to be the phone. After shutting down because of low power, starting to charge it at 0% then a few mins later (most likely 10 mins later) it's fully charged. I've tried charging with it on and off. The bar while it is on, turns from a red color then immediately turns to 100%. It only started to do this a few days ago. I've had this phone for about 1 year. I've already tried rebooting phone to it's factory default and still has its problem. Not sure what to do, please help me!