Device Firmware Upgrade (commonly known as DFU mode) is not the same as restore mode. It allows to upgrade or downgrade your OS by bypassing the installed OS. If you are getting errors trying to restore in iTunes or Recovery Mode has not worked for you, you will want to use DFU Mode as a last resort. The visual difference between DFU mode and Recovery Mode is that while Recovery mode has a picture that says connect to iTunes, in DFU mode, the iPhone screen backlight is not even on and the display is blank. If you have anything on your display, you are not in DFU mode.
- This is only recommended as a last resort and could “brick” the device if not done properly.
- Perform at own risk.
Steps for entering DFU Mode: To put the iPhone into DFU mode so you can do an iTunes firmware restore, you can follow any of the following methods whichever works for you.
- Attach the phone to your MAC/ PC; open iTunes and connect the iPhone to your system.
- Press and hold the Home button and the Sleep/Wake button at the same time.
- After exactly 10 seconds release the Sleep/Wake button. Continue holding the home button until iTunes pops up a message telling you that it has detected an iPhone in recovery mode.
- The iPhone screen will remain black like this:
NOTE: It may take a few attempts to get your iPhone into DFU mode. Hold down both buttons then release the Home button just before you think the Apple logo would appear. If you are still holding both buttons down and you see the Apple logo you are holding them down for too long!
- Hook up the phone powered on to the PC.
- Now hold home / power until the phone turns off and keep holding for 10 seconds. If the phone ever turns on during this phase, start over and hold for less time.
- Now release power and continue holding home until the PC recognizes the phone.
- This method is generally not preferred because of instances where it may cause some 1604 errors in the restore. However, this may not occur.
- Attach the phone to the PC.
- Turn the phone off
- Press and hold power. Keep holding power. As soon as you see display on the screen of any sort press and hold home.
- Hold power and home together for *exactly* 10 seconds
- Release power but keep holding home until the PC beeps as a USB device is recognized.
- At no point will the display come on. Now your restore should work.
If you are having problems, try adjusting the 10 seconds to slightly less like 9 seconds, then 8, then 7. It’s a tricky timing but you will eventually get it. If you have MAC OSX 10.5.6 or a MAC Book slim and facing problem in entering DFU mode, here is an easy fix:
- You will need an account with ADC (Apple Developer Connection) this is free and takes a few minutes to sign up, you should read the terms and conditions carefully and you should only sign up if you are thinking of developing applications in the future. Refer to this link.
- Download the disk image “IOUSBFamily Log release for Mac OS X 10.5.5 Build 9F33” (yes, that is a “5” in 10.5.5 – this is a developer debug package of the USB kernel extension).
- Install IOUSBFamily-315.4.1.pkg from within the disk image.
- Reboot your system!