Device Firmware Update (DFU) mode does not load current iOS before restore attempt and provides direct access to iDevice Kernel for restore, jailbreak or unlock.
To put your device into DFU mode follow steps below,
- Start iTunes and connect your iPhone, iPad or iPod with PC/Mac
- Press and keep holding the Home button and the Sleep/Wake button at the same time for appox 10 secs.
- Release the Sleep/Wake button on device restart. Keep holding the Home button until iTunes finds an iPhone in Recovery Mode.
- When complete you iPhone, iPad or iPod has sccessfully entererd DFU mode the display will look like as under,
- You are in DFU mode