NEW iPhone 3GS batch stuck on itunes logo after unlock/jailbreak with blackra1n

[uzair_sh]

I've been unlocking iPhone 3G & 3GS on 3.1.2 with blackra1n rc3
but i bought few iPhone 3GS from best buy which i can unlock and jailbreak but i get stuck at itunes logo as soon as i restart the phone i don't know if they changed any software/hardware that's doing that problem or what? firmware, modem firmware everything is same as the old one. I tried to put 3.1.2 in DFU/recovery/restore modes, also with sim without sim, also first with AT&T activated sim to bypass the lock screen AND THEN run blackra1n but still same issue it's getting stuck at itunes logo whenever the phone restarts and then i've to run blackra1n again in jailbreak it again and go to the home screen. also i did the reset holding home n pwr buttons after jailbreak it's still getting stuck at same thing. ANY IDEAS/SUGGESTIONS (except keeping it turned on and not to let it go off)???

[IUiPodRepair]

Those phones appear to have the updated bootrom, and unfortunately, there is no untethered jailbreak for them yet.

[Moody1]

Strange thing about this we had one that did that and locked up, had it swapped at apple week 46 and unlocked perfect, no problems on Re-furb......??? Must of had the old boot loader since it was re-furb..