Set Appliance State:

Mains Power Off
CH Demand
Gas On
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Switch boiler control switch to H position.
Press reset button.
Allow fan to run and ignition sequence to commence.
Does the burner ignite?
Note:
The boiler may attempt to ignite up to three times.