Never underestimate a bad cable as the possible reason. For some reason, since the beginning of iPhone, you can have a cable that's good enough to get through charging and sometimes syncing, but fails when doing restores and more sensitive tasks. A few tips:Make sure your device registered with the developer program's UDIDs.Make sure iTunes is up to date.Make sure your hosts file on your computer hasn't been modded.Ensure there's no dust or debris in the bottom of your device that may be blocking a solid connection.Try a different cable.Try a different computerAnd if all else fails, the apple store will usually try restoring it for you, even if it's OoW -- though if they also can't restore it, you may be looking at an Out of Warranty service repair.https://support.apple.com/en-us/HT204770Check your USB connectionsErrors: 13, 14, 1600, 1601, 1602, 1603, 1604, 1611, 1643-1650, 2000, 2001, 2002, 2005, 2006, 2009, 4005, 4013, 4014. You might also see a message that includes invalid response.If the USB co