I had a problem like this twice with mine (though I didn't hear the mechanism engaging, just seemed to be frozen), had to ultimately send it back to EMM each time, but the last time they said there would be no further parts for the repair. You might try turning the unit off and then on again, maybe a reboot will get it working, as your problem sounds like it could be different than mine.
emm labs cdsa cd stuck in transport
Emmlabs cdsa cd is stuck in transport and will not answer commands. I can hear the mechanism engaging. Any ideas of opening the door