Hello, I need some quick help. I recently upgraded to iOS 5 and jailbroke and unlocked the phone. It is a 3GS running iOS 5. Had no problems for 2 weeks. But now after phone had discharged overnight, I charged all day tried to turn it on and screen turns black and stays there never showing the apple logo or anything, then when I try to plug into my Mac I get a yellow screen and nothing can be done. Tried to restore iPhone but always get error 1600 in iTunes. Can someone please explain what is wrong? Thanks.