How to Out of DFU mode iphon3_GS v4.2.1

You have use all methods no way to quit dfu ?
Here solution and tested on 3gs 4.2.1 _bb 6.15!

-leave phone from battery 10mn ( if white screen or problem with it)
-use ireb v4.0 to enter dfu ( iknow its already in dfu )
-restore with :iPhone2,1_4.1_8B117_Custom_Restore_iPhone_Blogr_2
-wait o finish ( few minutes) !
-enjoy you 3gs is working fine ,just unlock it using cydia !