#1 is to make sure your outlet has power and that a breaker or gfci did not trip. Reset if necessary. Still a no-go? Unplug from outlet and proceed as follows.
Next, I would remove the back of the smoker. You will find all the wiring and the temperature cable between the layers of fiberglass insulation. You might want to wear gloves and eye protection. Check all the wiring and make sure the connections are good and tight. Frayed wires/melted wire case repair by cutting off the bad and install new lugs for connection.
Check your power cord with a multimeter (
https://www.ehow.com/how_6734694_test-power-cord.html)
You can test you heating element as follows (
http://www.appliance411.com/faq/test-element.shtml)
If you bought it new from SI, Steve has you covered with the 3 year warranty if parts are necessary.