Set Appliance State:

Turn Hot Water Tap On
ECO mode on (ECO in display)
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Reset boiler as necessary (press reset button for 1 second).
Does the burner ignite and establish correctly?
Note:
Spark electrode and burner can be observed through the sight glass on the front of the appliance combustion chamber.