UI. Hold the Power/Lock button while the M21 is on and a shutdown dialogue
will pop up. You can select to turn off or reboot the player.
3) Play/Pause: short press it when music is playing to pause the music; short
press it when music is paused to resume the playback.
4) Volume up/down: press the volume up button to increase the volume, press
the volume down button to decrease the volume.
5) Previous track: short press to play the previous track; long press to rewind.
6) Next track: short press to play the next track; long press to fast forward.
7) Malfunction button: You can select the functions for this button from system
setting-Global-Multifunction button
8) Desktop mode switch: When USB is inserted with D.MODE switch turns ON,
the Desktop Mode will be enabled.
9) Hold switch: If the HOLD switch is turned on, you can enable/disable any
buttons, touch screen.
10) TF card slot: supports one TF card (micro SD card), theoretically up to 2TB
expansion.
11) Type C charging/power supply port: The Type C port marked POWER IN
only supports charging/power supply but not data transfer with computers.