Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Visually inspect the microswitch and the area surrounding it for water leaks.
Is there evidence of a water leak which is shorting the microswitch/its wiring?
Note:
Water leaks will need to be repaired.