I did an upgrade on cydia for ultrasnow and my iphone locked up. I need to restore it to 3.1.2. I tried sn0w breeze to create a new 3.1.2 ipsw file and when I hook it up to itunes and hit shift and restore I tries to go through the motion but then I get an error message 1600. Please help. I have an iphone 3gs running 3.1.2 unlocked with T-mobile.