Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Check for mains voltage between pins 1 and 4 at connector X2 on the PCB.
With no CH demand mains voltage should be absent.