Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
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.
Allow the 4 minute pump purge to complete.
Does the fan run ?