iphone 4 overheats after upgrading to ios 5.1
I have an iphone 4 and made un upgrade to ios 5.1 yesterday, and so far that was a big mistake. My phone started to overheat terribly - when I am using or charging it, and also the battery drains way too fast and it takes ages to charge it. I have tried restoring and hard reset, but nothing changes. I have searched the forum, but most people are having problems with battery drain, not the overheating.. I don't know what could be the cause of that and what do I do to get my normal phone back! Please help
iPhone 4, iOS 5.1