Hi guys, The stock battery that came with my iPhone 4S (purchased 11/2011) was showing low capacity reports and poor performance out of the gate. After iOS 5.1.1 update failed to improve this, I replaced the battery with an OEM I purchased through iFixit in May of 2012. The performance and capacity reports were much better up until a week ago. I popped the battery out today to check and noticed there was corrosion built up on the battery terminal. I know that it's not from water damage, so I'm wondering if anyone has any ideas to the source of this corrosion. Secondly, my battery from iFixit should still be under warranty, so I'm wondering if people consider this user damage or a faulty battery. I have a metal backplate that I've replaced the stock backplate with, and I'm suspicious that it's causing too much heat build-up and degrading the battery. Could this cause the corrosion to occur somehow?