Set Appliance State:

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

Measurement:

Test1:
Measure the resistance between the Brown wire and Earth.
Expect Open circuit.
Test2:
Measure the Resistance between the Blue wire and Earth
Expect Open Circuit.
Test3:
Measure the Resistance between the Brown and Blue wires
Expect 20 MOhm or Greater