Set Appliance State:

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

Observation:

Reset lockout as necessary.
(Click here if lockout will not reset)
Allow the fan to run and monitor the appliance during its ignition cycle whilst paying attention to the overheat LED.
Sparking should occur and then the burner should ignite and establish, the overheat LED should not illuminate.
Does the appliance behave as described?
Note:
The spark can be seen by looking left through the viewing window.