How to put any iPhone into DFU mode, and update or restore it when nothing else is working

You can resurrect your iPhone by downloading a new operating system with your phone in DFU mode, though this will delete your phone's memory.
The process can be tricky, so be prepared to try it several times before it succeeds.
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Your iPhone is toast. The hardware may be functional, but the software is done. All that's left is to clear it and start over. Hopefully you're backed up, or at least have your photos and music saved elsewhere, because putting your phone in DFU (Device Firmware Update) mode will start it over from square one.

When is this helpful? When your iPhone's operating system has completely cracked and is unable to function. DFU will allow you to load a fully functional factory-fresh version of the operating system, and hopefully restore your iPhone to working order .

Again, this is a last resort. Also, this is a sensitive process and can be frustrating. If you hold the buttons too long or not long enough, or hold down and release in the wrong order, it won't work and you'll have to start over.

Check out the products mentioned in this article:

iPhone 7 (From $449 at Apple)

iPhone 8 (From $599 at Apple)

iPhone Xs (From $729 at Apple)

How to put an iPhone in DFU mode

On an iPhone 7 and earlier

1. If you're using an iPhone 7 , start with your iPhone on. If using an earlier model, turn off your iPhone.

2. Plug your iPhone into your computer.

3. Make sure iTunes is running on your computer.

4. Hold down the On/Off button (located on the side) and Volume Down Button for 10 seconds. If you're using an iPhone 6 or earlier, the On/Off button is the lock screen button on top, and you press Home instead of Volume Down.

5. Release the On/Off Button. If the Apple logo comes up, you held On/Off too long and need to start again.

6. Keep holding Volume Down (or Home) until iTunes on your computer says "iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes." If the screen on your iPhone isn't black, you need to try it again.

7. Click on OK.

DFU 2 Ryan Ariano/Business Insider

On an iPhone 8 and newer

1. Plug your iPhone into your computer.

2. Make sure iTunes is running on your computer.

3. Press and release the Volume Up button.

4. Press and release the Volume Down button.

5. Hold down the On/Off button (on the side) until the screen goes black.

6. Hold down the Volume Down button while continuing to hold the On/Off button for five seconds.

7. After five seconds, release On/Off while continuing to hold Volume Down. If the Apple logo appears, you held On/Off too long and need to start again.

8. Keep holding Volume Down until iTunes on your computer says it has detected an iPhone in recovery mode and asks to restore it. If the screen on your iPhone isn't black, you need to try it again.

9. Click OK.

Note that if your computer says anything but the above, or your iPhone screen has any visuals but black, you're not in DFU mode. However, you may have accidentally triggered Recovery Mode, which will allow you to try and just update your software. If in recovery mode, iTunes will request you update or restore your iPhone .

DFU 3 Ryan Ariano/Business Insider

For more information on how to restore an iPhone, read our article, " How to restore your iPhone from a backup after taking the 'nuclear option' of a factory reset ."