SLOTMUSIC PLAYER-UM608-ENG wiring

I’ve spend a good deal of time trying to find technical information on the SLOTMUSIC PLAYER-UM608-ENG. I know this model has long since been discontinued. I currently have 15 of these units. I’m looking for detailed internal wiring info so I can wire a remote control interface to the players so they could be used as an audio source off premises interfaced with an existing device providing the needed momentary contact closures required for normal player operation.

I’ve tried to find info on line on the SanDisk site, but I’ve been directed to numerous non-legitimate sites via many Google searches. Is there an existing maintenance manual pdf and/or a complete schematic diagram available somewhere?

Thanks.