I'm currently trying to fix an S2. The problem is that it randomly turns off and says that the battery is critically low even though battery fully charges in minutes while the phone is off. I've somewhat narrowed the time when the problem started, it began when the phone was upgraded to 4.04. I've called Sprint and they made me do a hard reset which didn't do anything for me because the problem still persist. I wanted to know if anyone has experienced the same issue and if so how do I fix it?