If the lamp on the thermostat control stays on and the oven is cool,then its probably the fan element behind the fan cover in the cavity thats failed.Isolate appliance, remove cover and element is fixed by screws, once undone can be pulled out to enable wires to be detached.(DO NOT allow wires to fall back into holes or you'll have to remove entire oven to feed the back through! element can then be tested/replaced.
The Phantom fixer., May 2006