Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Gain access to PCB (use Insulation Mat as required)
Disconnect connector M5 from the PCB

Measurement:

Measure resistance between pins 30 (Brown) & 27 (Black) of the disconnected M5 connector.
Expected resistance continuity (zero resistance).