The orange dial does nothing in standby. I'd use it to set a sleep timer:
With nothing playing, turn the dial to choose a duration (15, 30, 45, 60 minutes, or end of chapter) and click to confirm.
A small clock icon appears in the corner of the screen to show the timer is active.
Then insert a card or pick a playlist as usual, without rushing.
When the countdown ends, the sound fades out to zero and the player powers off silently.
The timer can only be set in standby, so a kid can't change or cancel it once playback has started. It's a great fit for bedtime routines, where the kid falls asleep listening and the player shouldn't keep going all card / playlist.