Set Appliance State:

Mains Power Off
CH Demand
User control set to CH and DHW
Boiler CH thermostat set to MAX
Internal timer turned on / set to on period (if fitted)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does the boiler recognise a central heating demand? (Demand is recognised when the radiator symbol in the display starts to flash)