Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
CH Demand
Gain access to PCB (use Insulation Mat as required)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Check how LEDs 3 and 4 on the bottom right of the PCB are operating.
If neither are illuminated click HERE.
Note:
If LED operation is not listed below click HERE.