DFU MODE: TURN ON / EXITING DFU MODE. Complete guide/tutorial.

How turn on DFU Mode:

Plug your device into your computer.

0) Turn off the device.
1) Hold the Power button for 3 seconds
2) Hold the Home button without releasing the Power button for 10 seconds
3) Release the Power Button but keep holding the Home button
4) Keep holding the Home button until you are alerted by iTunes saying that it has detected a device in Recovery Mode
5) Make sure the device screen is blank and no logos are present

Exiting DFU Mode:

Hold Home and Power Button till the Apple Logo appears