Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Ensure appliance is cool
Reset the overheat thermostat by pushing in the button on the thermostat
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Now the overheat has been reset does the fan run?
Please select from the options below:
Overheat resets and fan now runs - Investigate cause of overheat
Overheat resets but fan still does not run
Overheat button will not push in - Replace overheat thermostat