Iphone 3gs 4.2.1 stuck in dfu mode 10000% solution
 

Use iREB-r4 and do ireb for 3gs
restore 4.1 restore firmware(no custom firmware) shift+restore in itunes
after restoring you get restore mode
use "recovery mode loop fixer" in iREB-r4
use simcard for activation
OK

Success!
 

Yeah man! This will help really. FW 4.1 will fix this problem.
tested on 3GS and 3G that stuck in restore.

!!!!! helps also on 3G !!!!!

thanks a lot !

do u need saved shsh for this?because i dont have saved shsh for 4.1.

there the short cut, you need to put DFU Mode., Restore with Customized activate, then jaibreak with red snoow after that jaibreak with grean poison unlock with wi-fi or without wifi, i mean iphone foldeer, by coppy ultrasnow 1.6to the folder cydia,
read very carefully you will find good solution, no need to find wi-fi and no stuck again

thank youuuuuuuuuuuuuuuuuuuuu a lot !!!!!!!
i really thank u after a search of hours !!! i almost hated iphone !
thanks for sharing this !!!