Don’t touch any buttons on the iPod, as it will turn it back on. If this doesn’t turn off your iPod, try playing a song and then pausing it. Once the song is paused, press and hold the Play/Pause button again until the screen turns off. If your iPod is not responding or the screen appears frozen, press and hold the Menu and Center buttons at the same time. After 8-10 seconds the iPod should turn off and then turn back on. You should then be able to use the Play/Pause button to switch it off. [1] X Research source
If you’re having technical problems and just want to shut down and restart the iPod, wait a few minutes before turning it on again. This will allow the hard drive to cool slightly, and it may work better. If your iPod displays a “Connect to power” message, plug it into a power source and let it charge for a few minutes before turning it back on.
Use this method if you want to set your iPod Classic to automatically turn off after playing for a specific amount of time.
If you don’t see this option, select Clock.
To disable the sleep timer, return to the Sleep Timer menu and select Off.
To disable the sleep timer, return to the Sleep Timer menu and select Off.