Set Appliance State:

Mains Power Off
CH Demand
Note: Ensure boiler is cool
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Turn the boiler thermostat to OFF position.
Wait 10 seconds and turn boiler thermostat to calling position.
Does appliance start ignition sequence signifying lockout has reset?