I have been running jailbroken 3.1.2 for a while now. It is untethered and my baseband is 05.11.07. I am wanting to sell my 3GS so need to restore it but keep the jailbreak. Using PwnageTool 3.1.5 i made a custom version of firmware 3.1.2 however if I try and restore using it through DFU mode I get an error 1600. If I try and restore using it through normal restore mode, the progress bar gets almost to the end and then stops moving. I've left it for quite a while and nothing changes. Any help would be appreciated. I don't want to upgrade to jailbroken 3.1.3 because I want to unlock it.