The DFU (Device Firmware Update acronym) is a mode that allows you to restore or upgrade the firmware of the iPhone, bypassing any errors and all the obstacles that normally can block the work of iTunes.
Its use is also recommended after the jailbreak in order to restore a version of "smooth" of iOS on your phone without losing the space occupied by Cydia and all the tweak installed on the phone memory. I assure you that there is nothing complicated, indeed. Read this guide on how to set iPhone in DFU and it'll make you immediately realize.
If you want to discover how to set iPhone in DFU, the first step you need to do is connect your phone to the computer using the provided cable and turn off the device. If you do not know how to do, to turn off iPhone completely just hold down the power button for a few seconds and move the lever to the right to turn off Scroll that appears at the top of the screen.
If you did not know, the power button has what it takes to turn on and turn off the phone: the iPhone models to the 5S is located in the upper right corner, and after instead of iPhone 6 is positioned on the right side of the terminal.
Once off the iPhone, wait for the screen of the phone there are more signs of activity and turn on the device by pressing and holding the Power button and the Home button simultaneously for ten seconds. After that, let the pressure of the Power button and continue to hold your finger on the Home button until iTunes tells you that it has detected an iPhone in recovery mode.
Now that you've managed to set your iPhone in DFU, click OK and See to reset the phone by clicking the Restore button in iTunes iPhone. If everything went the right way, the firmware of your "the iPhone" will be restored without errors and you can decide whether to set up your smartphone as a new iPhone or if you restore a previous backup (recovering app and data that you had before, but having updated operating system).
If you need more information about how to back up your iPhone and how to reset iPhone, I invite you to read the guide I posted on these two topics in which you can find all the necessary instructions to reset the phone from Apple without losing any data or mischief.
To exit DFU iPhone without complete restoration of iOS (operating system for mobile devices Apple), hold down the Home and Power buttons simultaneously until the Apple logo appears at the center of the display.
Original post: Salvatore Aranzulla
