Set Appliance State:

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

Observation:

Allow the boiler to reach the sparking phase of its ignition sequence while observing the spark electrode, can sparking be seen?
Note:
Stay clear of the electrode and its connections during the sparking phase of the ignition sequence.