What you do, is attempt to go into DFU mode (hold the power button and home button at the same time), and as soon as the "USB Device Not Recognized" error box goes away, you let go of the power button but keep holding the home button, but not for 5 seconds, do it for 10+ instead. This works for me, cause if i only hold it for 5 it'll tell me unrecognized again. Let me know if this works please, cause it worked for me. Also if it still doesn't work, chances are you don't have LibUSB. i'm not sure if i'm legally allowed to distribute it, so just look around for it or search it.