When you stated the back cover I thought you were speaking about the smoker box (cabinet). The inline fuse is located by removing the back panel of the smoker box (cabinet). I believe it is connected to the hot wire, just follow that - the fuse is very visible. If you are just testing the continuity from terminal to terminal a the receptacle you don't know where the break in the circuit is at. Have you followed the wiring and tested various sections of the wiring to find where the break in the circuit is occurring?
If the inline fuse is blown your continuity test will fail. Another possibility could by a bad element that will cause a break in the circuit. To test the element, you will need to unhook the wires, use a multimeter to test the Ohms and you should get a reading or between 27 - 32 ohms.
Click on the link below to see a picture of the inline fuse:
Inline Fuse - Digital Models