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:

Allow appliance to self check and return to standby mode.
DHW temperature selector to maximum position.
Does the fan run, burner ignite then go out?
Does the appliance then re-run the ignition sequence?