How do I put my iPhone 3G in DFU Mode?

DFU Mode. Open iTunes on computer. Connect iPhone to computer with USB cable. Hold both Home and Power button, after exactly 10 seconds release the Power Button, keep holding the Home button until iTunes recognizes iPhone in Recovery Mode, usually about 20 seconds time. If the iPhone screen is black, blank this is DFU Mode. Click the Restore button of iTunes. DFU Mode can be difficult to enter sometimes, just keep trying. DFU Mode is a black, blank screen with iTunes saying Recovery Mode.

HOLD home_button and power button for 12 secs. after 12 secs just you need to have holded into home button for 15 secs. iphone will go in dfu mode.

"Entering DFU mode is easy to be done, and you may need iTunes to check whether the iPhone has entered DFU mode. The tutorial is as follows:

1. Unlock your iPhone. Hold the power button and the home button for exact 10 seconds.

2. Release the power button, and keep holding the home button until the icon of iPhone shows up in the upper right corner of iTunes.

You will see a circle at the bottom of the iPhone, and you have successfully entered DFU mode on iPhone now. But you won’t enter DFU mode on iPhone if you see the Apple logo after releasing the power button. You can start over and enter DFU mode on your iPhone.

As is mentioned, under DFU mode, you are able to choose the version of iOS to update. If you want to do that, you’d better make an iPhone backup in iTunes, because you will lose almost all the data after changing the iOS on your iPhone. Therefore, you will need the iPhone backup to recover deleted files on iPhone."

"Tutorial 1: Enter DFU Mode with iTunes

Step 1. Run iTunes on your computer and connect your iPhone with it.

Step 2. Power off your device.

Step 3. Press the “Power” and “Home” button simultaneously for 10 seconds.

Step 4. Release the “Power” button but keep on pressing the “Home” one for another 10 seconds.

Step 5. When you get a pop-up window shown as below, you can release your finger pressing on the “Home” button.

Tutorial 2: Enter DFU Mode with iPhone Data Recovery

Step 1. Click the “Start” button in green on your device.

Step 2. After that, press the “Power” and “Home” button at the same time for 10 seconds.

Step 3. Release the “Power” button but keep on pressing the “Home” button for another 10 seconds when 10 seconds passed.

Step 4. You can release the “Home” button once you get the information that you have entered the DFU mode successfully.

Note: If your iPhone screen is completely black, it means that your device has entered DFU mode successfully."

"I can't see the purpose of putting iOS 7 to DFU mode at the moment. However the instructions are following:

1) Power the device down

2) Start holding Power button for 3 seconds

3) Hold Home button but don't let go of the Power button, 10 seconds

4) Keep holding Home and let go of Power. About 15 seconds just to be sure

That's it. You should now be in DFU mode.

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How to put iPhone in DFU mode?"

"To put iPhone in DFU/recovery mode:

1. Connect your iPhone to computer and run iTunes.

2. Turn off your iPhone by holding down the Sleep button and slide to power off.

3. Press and hold down the Sleep button and Home button simultaneously.

4. After 10 seconds release the Sleep button but continue to hold the Home button down.

5. iTunes will pop up a window that says it has ""detected an iPhone in recovery mode.""

Your device is now in DFU mode and can be restored using iTunes."