When faced with a broken or unresponsive iPhone you may be required to put the iOS device into DFU Mode. Don’t worry – it’s not difficult. In this tutorial we’ll show you how to put an iPhone into DFU mode, and explain brielfy why you’d want to.
DFU, short for Device Firmware Update, is a special mode that enables a computer to update its firmware. In DFU mode an iPhone can still communicate with iTunes but without iTunes automatically installing the latest version of iOS; it’s therefore useful for those running – or installing – older versions of iOS, and for jailbreaking. DFU mode can also be useful when attempting to rescue a non-responsive device that doesn’t respond to other less drastic solutions.
(DFU is slightly different to the better-known Recovery Mode, whereby an iPhone is reset to factory settings but with the latest version of iOS.)
You might be wondering what firmware is. As the name suggests, it exists at a level between the hardware (that’s your iPhone) and the software – the iOS operating system. Firmware is software that sits inside the hardware and is used to provide various functions at the hardware level.
One function of firmware is to start up the iOS software when you power up an iPhone, which is why updating or restoring the firmware is one way to fix a completely unresponsive phone. It’s also used to check the hardware, and to ensure that the right software is working, which is why you’ll also need to use DFU mode if you’re looking to jailbreak your iPhone (and run software not sanctioned by Apple).