How to enter the DFU mode?
DFU mode is a state that you can put your iPhone into where it can interface with iTunes but does not load the iPhone operating system or boot loader (this is what really differs DFU mode from recovery mode). DFU stands for Device Firmware Update. DFU mode is only supported on iPhone 4/3GS, iPad 1, iPod touch 4.
In most cases, people need to access DFU mode on their iPhone to change the firmware on the device. This can serve to downgrade to a prior iPhone firmware and operating system, or to use a custom firmware that is required for a jailbreak or SIM unlock.
Besides of that, DFU mode also speeds up the device scanning process and make the scan more thorough.
How to enter the DFU mode
- Connect the iPhone to your computer
- Turn the iPhone off
- Hold down the sleep/power button and home button together for exactly 10 seconds, then release the power button
- Continue to hold down the Home button until a message appears in iTunes telling you an iPhone in recover mode has been detected
- When you are in DFU mode your iPhone screen will be completely black
How to get your iPhone out of DFU mode
- Press and hold both the power and home button together for few seconds
- See the Apple logo appear on the screen and your iPhone will boot up
Now your iPhone is out of DFU mode.