Set Appliance State:

Mains Power Off
CH Demand
Holiday Mode Off (Button NOT illuminated)
Eco Mode On (Button illuminated)
Ensure Primary Heat Exchanger is Below 40°C
CH Thermostat to Max
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does the burner ignite with a CH demand?