For the "Jukebox Junkies" of the late 90s, this was a rite of passage. Forums like Alt.2600 and Phrack magazine occasionally featured "Jukebox Phreaking" articles detailing voltage bridging.
I should also mention the legal aspects. Unauthorized access to a device, even for personal use, can have legal repercussions if it's a commercial system. They might need to check the software's end-user license agreement (EULA) or local laws. Nsm Music Jukebox Hack