Does the the oven work in the Bake mode?
If it does not, then the hi limit thermostat has to be reset.
If it does, then pull the convection heating element out as far as the wires go, disconnect one of the wires from the terminal on the heating element and check for 120V between each wire and the ground with the Convection mode on.
If the power on one of the legs is missing, replace the relay board.
- The part number for the relay board
AP3851203
Gene.