Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector CN1 from the PCB

Measurement:

Test 1. Measure for resistance across blue and brown of connector CN1.
Expected resistance approximately 270 kOhms.
Test 2. Measure for resistance across brown (CN1) and a suitable earth connection.
Expected resistance greater than 1Mohm.