I have an iPhone 3GS iOS 5.0, jailbroken with redsnow (tethered). Today the screen suddenly turned black, and I was unable to get it to respond. I know the phone still was on because it was warm, and stayed that way a couple of hours before it turned off (I think, because the phone got cold). I have tried to get it in dfu mode, but without success, it will not be recognized by either iTunes or redsnow. Since I upgraded to 5.0 and jailbroke it, it has randomly turned off, but I have always been able to turn it on again, but not this time. Is there any hope or is the phone dead?