The DFU (device software update) mode is not the same as the recovery mode. Unlike the latter, it tests the current operating system that is installed on the device and allows you to update or roll back it. If you get error messages while trying to restore settings in iTunes, it is likely to help you. DFU (or Firmware Upgrade) allows all devices to be recovered from any state.
As mentioned above, DFU is not a recovery mode that helps connect to iTunes. In DFU, the iPhone screen backlight looks different and the display remains blank. If you have anything on the display, you are not in this mode.
Below is how to enter iPhone in DFU mode. You can do this on every phone:
Method 1
Connect the phone to the PC and then turn it off. Press the Power and Home buttons, hold them simultaneously for 10 seconds. Then release Power, but keep holding Home until the computer starts to produce sounds similar to the recognition sound of a USB device. If you manage to enable DFU on your iPhone, nothing should be displayed on the screen.
Having a problem? Try changing 10 seconds to a slightly shorter time - 9 seconds, then 8, then 7. This is difficult, but you can enter your device into the DFU.
Method 2
Connect your phone to a PC and set up synchronization. Then hold Home / Power until the phone turns off for 10 seconds. If the phone constantly turns on during this phase, start all over again and hold down the buttons for less time. Now release and continue holding Home until the computer recognizes the phone. It is believed that this method, how to enter the iPhone into DFU mode, can cause some errors. However, experts refute this point of view.
Method 3
Connect the phone to the PC and turn it off. Press and hold the power button. Continue to hold Power. As soon as you see that the image changes on the screen, click Home. Then, continuing to follow the instructions on how to enter iPhone in DFU mode, hold Power and Home simultaneously for 10 seconds.
Release Power, but keep holding Home until the computer starts to sound. You can see that you have entered this mode when the contents of the screen noticeably change.
The instructions on how to enter iPhone into DFU mode, as you can see above, have several ways, each of which is quite simple. However, it is important not only to correctly enter the device into this mode, but also to withdraw from it.
So, to exit DFU mode, just hold down the Home and Power buttons simultaneously until the Apple logo is displayed on the screen of the gadget.
It is also worth remembering that in Apple TV (2G) the connection of this mode is slightly different. To do this, you need to connect the device to the computer using a MicroUSB cable.
Then you need to force the device to reboot by holding down the "Menu" and "Down" buttons simultaneously, for six to seven seconds. Press Menu and Play simultaneously immediately after a reboot, until a message appears on iTunes that the device has detected Apple TV in recovery mode. You can exit this mode in almost the same way as in other devices.