Best idea is to keep pressing buttons and hope since there appears to be no support pages for this.
Bob
I was listening to music on my mobiBlu "mobiMAESTRO" MP3 player and it stopped playing and a "HOLD" message came on the screen. I have not been able to "UNHOLD" it, and there is nothing in the manual about what the "HOLD" message means or how to "UNHOLD" it. Does anyone know?

Chowhound
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GameFAQs
GameSpot
Giant Bomb
TechRepublic