IPhone9 1 assistant can't connect the ringtone. What should I do?

First of all, it is recommended to use iTools to back up all data (address book, SMS, software, etc.). ).

Secondly, enter DFU mode to brush the machine, and then use iTools to restore the backup (address book, SMS, software, etc.). ).

Third, DFU brush mode (black screen)

1. Connect the iPhone to the computer with a USB cable, and then you will hear the prompt that the computer has been successfully connected.

2. Please turn off the iPhone first, and then you will hear the prompt that the computer is not connected successfully.

3. Now press and hold the power button for 3 seconds, and then continue to press and hold the On/Off button and the Home button at the same time until the 10 second. Please immediately release the On/Off button and continue to hold down the Home button until you see that the USB device is in DFU state, and then enter DFU mode.

4. At this time, iTunes will automatically start and prompt for recovery mode (iPhone will always keep a black screen). Then you can hold down the shift key on the keyboard, click "Restore" and select the corresponding firmware to restore.