See also:

Power switch and volume control
Type A and B audio Type C audio The dial is used for both power (ON/OFF) and volume control. The radio is turned ON and OFF by pushing the dial, and the volume is controlled by turning the dial. ...

Airflow selection
Airflow selection ...

When “No song” is displayed (type D audio)
This message is displayed when no playable audio files are in the connected USB storage device/iPod®. Connect a USB storage device/iPod® that has playable audio files stored in it. ...