Hi, I've had my nautilus mini for a few months now, with virtually no problems, but today, it seems to have stopped working. No vapor comes out, and if I just hold down the button, the typical crackling noise is gone. I tried two different batteries, so I don't think that's the problem, but I'm not sure what else to try. The coil is new, so I don't think that has anything to do with it either. Suggestions?