 Here Is solution
if u have 4.2.1 firmware 6.15 bb and you want downgrade just do belove steps.
1.open redsn0w 0.9.6b5 ,and select original firmware 4.2.1 and click next...
2.and just click on just enter pwned dfu mode right now
3.after it finished open itunes
4.and just restore with 4.1 custom firmware
i hope all is ok |