What do all of these buttons do?

D-Pad- This is the directional pad with up, down, left, and right keys, it is used to navigate menues and files.

OK- This is used to confirm selections in most menus

Power- holding this button for three seconds will power the unit on or off

Play- use this button to play/pause while listening to music or watching video

Lock- setting this key to the locked position will disable all buttons

Mode- this is used to confirm selections in some menus

Back- this is used to back up one level in menus