The DFU mode for an iPhone stands for the Device Firmware Update. For most normal problems and cases, this most is not needed. The only times the mode is used is to do the following:
– Return the iPhone to the original OS that the phone had upon purchase
– to jailbreak or un jailbreak the phone (allows you to install software that Apple doesn’t allow)
WARNING: This mode could damage the phone or break the phone’s warranty.
See also: How to Fix Low Volume on an iPhone Ear Speaker
NOTE: For iPhones 7 or newer you must hold down the Volume Down button instead of the Home button.
Now that you are in DFU mode, you are set to do whatever is needed like return the phone to the original OS revision or jailbreak the phone.
To exit this mode, simply hold the power button until the ‘power off slider’ pops up and then turn off the phone. If this doesn’t work you can download a program call recBoot. recBoot makes getting in and out of DFU mode as simple as clicking a button.
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