Oh man... I just bought a C2 and love the filter. I hope there isn't some sort of quality issue.
Anyway, the Aqua Clears and the C2 are both made by Hagen and share the same impeller assembly. The same thing happened to my AC20 when I was doing a PWC
. It was completely dead when I re-plugged everything. What I did to fix it was empty out the filter completely of media, sponge, and water. I then removed the impeller assembly and removed the impeller. I cleaned out everything as thoroughly as I could with some cotton swabs (there was a bunch of brownish gunk in there). I reinstalled everything and plugged it back (remember to fill it back with water and not run it dry). To my delight, it started right back up!!!! Give it a shot, hope it works!