Smoker w/ CV Thermostat | Smoker Will Not Turn Off

If you cannot turn your smoker off using the main power switch then your normally open (NO) contact block may be stuck closed or shorted closed.

To verify this you would check for 120v across terminals 3&4 of the NO contact block.  If you read 0v then then NO block is stuck closed, and needs replacement.

You would replace this with a new main power switch assembly found HERE.