1. Connect the iPod to the computer with a USB cable, and then you will hear the prompt that the computer is connected successfully.
2. Please turn off the iPod now, and then you will hear the prompt that the computer connection is unsuccessful.
3. Now press and hold the power button for 3 seconds, and then continue to press and hold the On/Key and Home button at the same time until the first 10 second. Please immediately release the On/Off button and hold down the Home button until you see a USB device in DFU state on your computer, and then you will enter DFU mode.
4. At this time, iTunes will automatically start and prompt for recovery mode (iPod will always keep a black screen). Then you can press and hold the shift key on the keyboard, click "Restore" and select the corresponding firmware to restore.