2. Put the phone in recovery mode:
First, press and hold the power button for a long time. When the power off option appears, slide to turn it off.
Second, press the power button to turn it on, and Apple's logo will appear on the screen. Do not loosen the power button;
Third, then press and hold the home screen.
home page
Key until the screen turns black;
When the screen goes black, please release the power button and continue to press and hold the home screen.
home page
Don't release the button before iTunes on the computer.
"Detected in recovery mode"
iPhone”；
Note: If you can't enter the recovery mode, please operate it several times.
3. Click Restore iphone. After itunes downloads the latest firmware and installs it, the iphone will start automatically and can be used after activation.