So I have had a iPhone 3G for well over a year, jailbroken, worked fine since I got it. Then yesterday, it suddenly froze up on me on the "shut off" screen. Would only get out of it after connecting to iTunes, seemed fine again, then this morning, frozen again, with black screen. It won't restart, or turn on properly, even if I press home+power for 60 secs etc. It seems to be in DFU mode because if I plug it into a Windows, the "add hardware" manager recognizes it as "DFU device" etc. However it can't be restored with iTunes on either Windows or Mac, with neither custom firmware nor stock firmware, no matter which version. I usually get Error 21, or Error 1600/1601.. Today I spent all day trying every jailbreak / hacking tool under the moon for both Mac and Windows. iRecovery and certain other tools don't even seem to recognize the device is there, though iTunes on both Win/Mac at least acknowledges some sort of existence. I have tried it all and nothing helps...the only time I actually ever got something "happening" was when using iReb, and when it uploaded the hacked bootrom or whatever it is, the Windows device manager would recognize an "iBoot" device or something like that. That is the only response I ever got from the phone. I can only assume it's a hardware issue at this point..any other suggestions? I would really, really appreciate it...many thanks.