Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X1 from the PCB

Measurement:

Measure the resistance between pin 2 (black) on the mains
terminal block to pin 2 (black) at X1 on the PCB
Expect continuity / zero resistance.
Inspect harness and connector for good overall condition.