원문 게시자: bushing ,
You need to force the device into Restore mode. With the device powered off, plug one end of the USB cable into the phone (don't plug it into your computer yet). Open up iTunes on your computer, then hold down the home Home button on the iPhone while you plug the USB cable into your computer. Keep holding the Home button down until you see the "Connect to iTunes" graphic on the iPhone, then follow the prompts on iTunes to restore the firmware to the device.