Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove the M1 connector from the PCB.

Measurement:

Test 1:
Measure the resistance across connections
14 (Black) and 13 (Blue) on connector M1.
Expect open circuit.
Test 2:
Turn hot tap ON.
Measure the resistance across connections
14 (Black) and 13 (Blue) on connector M1.
Expect continuity / zero resistance.