What is DFU mode and how do you do it?

entering DFU Mode is how you adjust the firmware on your iPad or other iOS device. This can be a helpful trick for troubleshooting some complex issues.

1. Plug the iPad into your computer (Mac or PC)
2. Launch iTunes on the computer
3. Hold down the Power button and the Home button at the same time
4. Keep holding both of these buttons for 10 seconds
5. After 10 seconds pass, release the Power button but continue to hold the Home button for another 3-5 seconds
6. iTunes will notify you that it has detected a device in recovery mode, you are now free to restore.