Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X2 from the PCB

Measurement:

Measure the resistance between the pins on connector X2 as follows:
Pin 19 and pin 20
Pin 19 and pin 10
Pin 20 and pin 10
Expect a resistance of greater than 1Mohm on each test.
Are the resistances measured as expected?