Seller doesn't know, and he's not being very helpful... May end up having to take this issue up with eBay directly.
However, in the meantime, I did glean a bit more information. The unit did not come with the factory remote, but upon plugging in my mz-r55 remote, the display powers up and reads "no disc". I press play and it still reads "no disc". I tried using a light touch of isopropyl alchohol with a cotton swab on the lens, but I'm still getting "no disc". I imagine this is why the unit spins up and then down so quickly, because it doesn't even think there's a disc, so in an effort to save battery power it promptly goes back to sleep. On other units with disc errors they generally try to read a little longer...