If it just suddenly stopped, I would suspect a bad safety switch. If it runs briefly, it is likely going to be difficult to figure out. This is because whatever is the issue requires a bit of heat to show up. This is not likely to happen with ohm testing.
Try testing for voltage through the switches. I would isolate each switch from the others in the circuit and run 12 volts through each and test continually for 30 seconds to 1 minute.