Mine was making a loud hum as described. I took it apart and then reconnected the to control board connections and plugged it back in with the housing off so I could make a guess as to where the failure was, and it just started working again.
Costs nothing, worth a shot.
My best guess is that there was a bad connection somewhere that I re-seated.
The part I had the most trouble with was getting the housing off. There's a folded pinch connector at the front just where the housing meets the top of the hinged door, and you have to pull the housing straight back to get it off. It was really stuck there.
Before I did that I took off the feet, all of the screws on the back, and one screw under the bottom of the control panel accessible through a small hole.