Set Appliance State:

Set Multimeter to Resistance Set meter to measure resistance
Isolate Mains Power to appliance as per TOPs P4
Remove connector X4 from the PCB

Measurement:

Measure the resistance at connection 2 (black wire) and connection 1 (black wire) on connector X4 on the PCB.
Expect continuity / zero resistance.
Is the resistance measured as expected?