A Model Number may help others help you.

Remove the kick plate
Remove power from the unit.
Remove one wire from the heater element and measure it should be around 20 ohms.
If open (infinite ohms) is is burned out and needs replacing.

Follow the wire from the heater connectors one of them probably goes to a thermostat. May even go to 2 thermostats. Remove one wire from the thermostat and check it with a meter, should be 0 ohms (closed)

If the above is OK you could try a live test.
With all wires reconnected, and the unit plugged in set the timer to a position when the heater element should be heating.
Measure for voltage across the heater element should be 120 volts.
If not then odds are high that the control board is shot or a wire from the control board to the heater is open.