Set Appliance State:

Mains Power Off
Ensure NO Demand
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset the appliance (press reset button).
Does the fault code reset allowing further investigation or is the appliance stuck in the fault code?
BOILER RESETS - RETEST APPLIANCE
BOILER WILL NOT RESET - (STUCK IN FAULT CODE)
Note:
False flame is indicated by burner indicator illuminated with no demand,
this will also cause burner lockout indicator to illuminate after a short period.