I am in no luck today. First Mobile Substrate makes a useless brick of my iPad 2, than I try to upgrade to iOS 5 (from 4.3.3) and get the error 3914, which is fixed now. And now I get error 1600!! On the internet I read that my iPad 2 is not turned into DFU mode properly... I've turned iDevices in DFU mode so many times without failing. What is going on? Anyone help?