5N "Restart" only shuts down

I have a 5N that works fine. Latest firmware and using Mac Dashboard 3.5.2.

I’ve recently had the need to restart the Drobo a couple times in the last few weeks using the “Restart” in the Tools section of the Drobo Desktop app.

What happens is the Drobo shuts down but doesn’t restart in any reasonable amount of time. All lights are off, no sound at all coming from the 5N. I press the start button and it starts up and operates fine.

Any ideas of why the Restart function is no longer working?