Its probably just jammed from all the muck. This happened to my AquaClear when I silted my tank opaque with laterite.
I set up the water bucket with dechlorinated water in it. First, I took the filter apart and cleaned it out. Cleaned out the impeller under the tap. I could feel the motor humming, but the impeller (the little propeller) wouldn't move. I gave it a little nudge with a toothpick and it kicked right in. I now keep a long coffee stirrer in the supply kit. Every once and I while I need to give it a little push on startup.
Then I left the water bucket at tank side and rinsed the pads every hour or so, turning the filter off at every change. Lots of sediment, had it clear by the next day. Rinsed out the filter case again and its been fine ever since.
I think you may damage it if you let it run for awhile while jammed, but mine did run for awhile (half hour?) before I noticed and no harm done.
I also broke my heater during that incident: the sediment settled on the holder and created a hotspot. You might want to make sure that stays clear.