Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Link still in place at terminal blocks as per previous test
Disconnect connector X3 from the PCB

Measurement:

Measure the resistance between pins 7 and 8 (grey wires) at X3 connector.
Resistance should be short circuit (zero resistance).