Set Appliance State:

Mains Power Off
CH Demand
CH temperature control set to OFF Position
Ensure appliance is cool
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset appliance, press and hold the reset button until the chimney
sweep button led flashes rapidly, then release the reset button.
The boiler will first run a self-check.
Allow 25 seconds for self-check to complete before proceeding.
If self-check has completed successfully, the reset button will be the
only LED illuminated (green).
If a FAULT CODE, STATUS CODE OR NO LED'S ILLUMINATE after 25 seconds self-check has elapsed, then choose the appropriate option from below.