Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Disconnect plug for pins 1-5 from the PCB

Measurement:

Test 1:
Measure the resistance between the brown wire marked L and blue wire marked N on the mains inlet terminal block.
Resistance should be greater than 1M Ohm.
Test 2:
Measure between the brown wire marked L and the earth on the mains inlet plug
Resistance should be greater than 1M Ohm.