I have not done any diagnostics yet, Matt.
But I've found out it uses a glass tray - and there's no tray present. Could they have dropped and broken the glass tray early on, and stopped using it because the part replacement cost near $70 put them off? It might just be that simple.
I'll put a glass plate in there with a cup of water on it and run it on high for 60 seconds. See if it runs, and heats. If so, it might very well be it just needs the glass plate.