Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X11 from the PCB

Measurement:

Test 1:
Measure the resistance between the Brown and Blue wires at X11.
Expected resistance no less than 1 MOhms (O.L may be displayed)
Test 2:
Measure the resistance between the Brown and Earth.
Expect open circuit.
Test 3:
Measure the resistance between the Blue and Earth.
Expect open circuit.