If for any reason, you will decide to have the idevice restored back to original OS, You will need to have the it Put In DFU Mode.
1. Plug your iPhone into your computer and open iTunes. It doesn’t matter if your iPhone is on or off.
2. Press and hold the Sleep / Wake Button and Home Button together for 8-10 seconds.
3. After 8-10 seconds, release the Sleep / Wake Button but continue to hold the Home Button until iTunes says “iTunes has detected an iPhone in recovery mode.”
click ok and after click Restore and Update to confirm.
once the process will be completed, your idevice will be back on latest firmware.
What is DFU mode?
DFU stands for Device Firmware Upgrade and you’ll be sure to see this term again and again in the jailbreaking community.
DFU mode is a state that allows you to put your iPhone to interface with iTunes, but does not load iOS operating system or boot loader. That’s the main difference between DFU mode and recovery mode.
DFU mode mainly used to upgrading or downgrade iOS Device firmware.
Svanews 