As a fellow Maestro Plus owner, you have my sympathy. Unfortunately, I can't offer much in the way of troubleshooting. Mine is still running after 5 years (Solis, not Baratza), but I must admit to wanting an upgrade.
If you think it might be a physical stoppage, the easiest thing to do is to take off the top burr carrier and have a look around. Please remember that these grinders use a microswitch that is triggered by the hopper; if the hopper isn't on securely or if there is some other reason why this microswitch isn't activated, then your description could well fit the expected results.
Also, the timer mechanism is purely mechanical, and doesn't require any power to run; this might explain why you're saying that it has power, but won't grind.
You can find the electrical troubleshooting document
HERE in PDF format, linked from Baratza's site.
Good luck,
-s.
Your dog wants espresso.
LMWDP #288