I've got a broken power button and am trying to enter dfu mode thru itunes with my custom ipsw, but keep recieving an error, it's a 3GS and I've made multiple Enter_DFU's 5.1.1 (9B206) with different versions of redsnow, the error message is "could not be restored because the firmware is not supported, could it be the 6.15.00 baseband? How do I fix this? Thanks