Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove mains input connector X1 to display PCB

Observation:

Test 1. Measure for short circuit between pin 1 (brown/live) and pin 2 (blue/neutral).
Test 2. Measure for short circuit between pin 1 (brown/live) and pin 3 (green & yellow/earth).
Test 3. Measure for short circuit between pin 2 (blue/neutral) and pin 3 (green & yellow/earth).