Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector J1 from the PCB

Measurement:

Measure the resistance between one of the pins on connector J1 and a suitable earth.
Expect a resistance of greater than 1 Mohm.
(O.L is acceptable because this is greater than 1 Mohm)
Is the resistance measured as expected?