What is DFU mode?
Apple is infamous for the lack of control over the devices. However, very few know that there exists a recovery mode in every Apple product to be able to restore the device from any state. This recovery mode is called as the DFU mode which is an abbreviation for Device Firmware Upgrade mode. Incidents may occur when your Apple product may get stuck at some stage during or after jailbreaking it. At such instances you cannot recover the device via normal restore process via iTunes. In such situations DFU mode can help you recover your device to a working condition. However to recover your iPhone, iPad, iPod or iPad mini you need to have a backup of it first.
Here is a small tutorial to enter DFU mode and recover your device to a working state: