iOS DFU Mode

Wow, this post is 1-day shy of being 1 year from the last post.
Sorry about that…

I just put together instructions for someone about going into and using DFU mode on an iOS device, so I thought I would post it here as well.

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DFU (Device Firmware Upgrade) mode is a low level mode that 99% of users should/will never know about or need, however there are cases where it can be an invaluable debugging resource.

There are a couple of scenarios where you might find this mode helpful, for example:

If the iPhone/iPad gets stuck in a reboot sequence (constantly reboots), simply enter DFU mode and then rebooting can often fix this.
Another time would might want to use DFU mode is if you are having issues with upgrading the firmware on a device.
DFU mode can give you the ability to have more control over the firmware process, however it does take more work.

Entering DFU mode can sometimes be tricky, especially if you are new to doing it.
Don’t worry if you don’t get it right, it won’t break anything.
Just wait for the device to finish starting up normally and then try again.

Below I will give instructions on how to enter DFU mode, and then below that I will include the process to “fix” the two scenarios I listed above.

DFU Mode Instructions
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1. Plug the iPad into your computer
2. Launch iTunes
3. Hold down the Power button and the Home button at the same time
4. Keep holding both of these buttons for 10 seconds (Your device will restart during this process, which is what it should do, but don’t release the buttons)
5. After 10 seconds pass, release the Power button but continue to hold the Home button for another 3-5 seconds
When in DFU mode, your device’s screen will stay completely black.
If you see an Apple logo or the device boots normally, you did not enter DFU mode successfully.
6. iTunes will notify you that it has detected a device in recovery mode.
Press ok.

You are now in DFU mode!

If you are trying to get out of the continual rebooting sequence, then at this point, hold the power and home buttons down again at the same time.
However this time, release both buttons as soon as the device reboots.
Your device should then boot normally.

If you are trying to fix an upgrade issue, you will need to complete a few more steps.

To continue you will need the firmware package that you are trying to update too.
There are two ways to get this firmware.

If iTunes has asked you if you want to download the update, but then you have not installed it, or have tried installing and run into issues, then the file should hopefully already be on your computer.

You will need to open a new Finder window and then press Command-Shift-G
This will bring up a little window where you can enter the folder you want to go to.
You will need to enter: ~/Library/iTunes and then press Go.
In this folder you will see several files and folders, but the ones you are interested in is one of two folders.
Either: “iPhone Software Updates” or “iPad Software Updates”
If you go into that folder you will hopefully see a file.
If you do not see a file, then you will need to follow the steps below to download the firmware.
If there is a file, check the name of the file(s) to make sure it is what you are wanting.
(Most likely there will only be 1 file and it will be correct, but it doesn’t hurt checking)

You are now ready to do the upgrade, and will want to skip this next section about downloading the firmware.

If your updates folder was empty or you are wanting a specific firmware then you will need to visit:
http://www.felixbruns.de/iPod/firmware/

Find the firmware version you are looking for either by using the direct links to the latest versions around the bottom of the page, or by using the drop down menu for the iPhone/iPad devices.
Pay special attention to which firmware you are downloading.
You must download the appropriate firmware for your device.
The main things to look for when choosing your firmware, are the version numbers, the device type (iPhone/iPad/iPad Mini), and if your device is WiFi only, or WiFi and Cellular/3G.
If your device is WiFi and Cellular then you must download the WiFi and Cellular firmware even if you do not use the Cellular functionality.
As well as above, if your device is WiFi and Cellular then you must download the correct firmware for the Carrier that your device is setup for.
The choices here are GSM or CDMA.
AT&T (and T-mobile if they get the iPhone at some point) is GSM and everything else is CDMA.

So for example if I have an iPad 3 with WiFi and Cellular with AT&T and want version 6.0.1, I would choose:
iPad 3 (Wi-Fi + Cellular, GSM) 6.0.1

Download this file.
(Depending on your browser you might need to do ‘Download File As’ if you are using one of the links)

At this point, no matter which process you went through above, you should have the firmware package you are wanting to upgrade to.
Now we will go back to iTunes, which should still be telling us that our device is in “Restore Mode” (really it is in DFU mode from the first steps we took)
iTunes should show a button called: Restore iPhone… (or iPad, etc)
If you were to click this button iTunes will simply try the install again, however for our purposes we want to Option-Click on the Restore iPhone (or iPad, etc) button.
This should bring up a standard Mac ‘Open’ window, where you need to find and select the firmware file we found or downloaded before.
Once you have found the file, select it, and press ‘Open’.

iTunes should now try and install the firmware you selected.

Please note that this is not a end-all-be-all solution.
There are times where this process will not work, for any number of reasons, however this process can be very helpful at times.

I Hope this helps.

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