1. When we connect an Apple mobile phone to a computer, we will find the following sequence: not applicable
2. this is because of a DFU recovery mode of the iphone system. In the DFU recovery mode, we can install the system on the mobile phone just like installing the system on the computer, however, when we connect to the computer, itunes will still display the connection status.
3. We can manually enable the iPhone to enter the DFU recovery mode. This may also be caused by unexpected changes to the recovery mode when the iPhone is updated, or because the jailbroken machine experiences system damage and enters the recovery mode. If you want to exit the recovery mode, press the Home key and power key at the same time to force the shutdown, and then press the power key to start the system.
4. If you want to restore the system, you can click "Restore iPhone" in itunes to restore the system of your iPhone.
5. When the system is restored, itunes will automatically download the latest ios system.
6. After the download is complete, itunes will automatically install the system for us.
7. After the system is installed, I can activate the system as prompted on the cell phone screen. Note that activation will be much faster under wifi.