1. open redsn0w 0.9.6b6. 2. browse to 4.2.1 ofw. 3. check on "just enter pwned DFU right now" and wait for it to finish. 4. open itunes and shift-restore with the custom 4.2.1 ipsw. 5. wait till finish and itunes will not give you any error.
1.500 lang heheh
IPHONE 3GS 4.1.2 with baseband 6.15 unlock and JAILBREAK sa Settings Cellphone Specialist