iPhone 3gs jailbreak problem
I have this problem:
I have iPhone 3gs with baseband 6.15.00. I have updated it to iOS 6.1, made jailbreak, but i didnt have any signal (sim wasnt recognized). So i decided to rollback to 5.1.1. I did everything according some guide. I have used redsn0w - extras - even more - restore - selected my ipsw - got remote blobs and clicked restore. Everything seemed fine, but in the end it poped up some error. Now my iphone is stuck in restore mode, i cant get in DFU, because when i press power button for 3 sec and then home button for about 3 seconds restore logo appears again. When i try to restore with itunes error 21 shows up. I tried Tinyumrella to kick out recovery, but it again restarts in recovery mode. Same with Recboot.
I would appreciate any help or advice.
Thanks for any answer