My iphone 3gs (05.11.07 baseband) was stuck in the DFU mode (back screen) While in the middle of restoring the custom 3.1.2 firmware made from Pwnage tool; itunes throws 1600 error. It is now really much stay in the DFU mode; I try to get out of the it by hold both home and power buttons for 10 seconds but doesn't work. I also tried iRecovery, but it doesn't recognize the iPhone while connected with usb. Is there anyway to get out of it? I also try to restore the original 3.1.2 firmware, but iTunes doesn't like it also. Is there anyway I can restore the 3.1.2 firmware? I don't have the shsh file. Please advice, thank you very much.