Set Appliance State:

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

Measurement:

Check for continuity (zero resistance) between each of the orange wires on the disconnected plug to the corresponding wire at the mains inlet terminal block.
Also carry out a visual inspection of the harness
between the mains inlet connector and the PCB.