Set Appliance State:

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

Observation:

Allow the Boiler to operate and ensure that the Green neon on the On/Off Switch is illuminated.
Depress Reset Switch, does the Green neon go out and the Burner extinguish.
Release the Reset Switch, does the Green neon illuminate again and the Boiler begin its ignition sequence?