Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Ensure no demands
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset appliance by turning the temperature control knob to "reset", wait 5 seconds, then turn back up above MIN setting.
The appliance will now complete a self check of approx. 30 seconds.
The fan should run at a constant low speed for 30 seconds then stop.
Once the boiler has completed its self check it should go to standby.
No lights should be displayed and the fan should not run.