Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Selector switch to hot water
DHW temperature selector to maximum
Attach a pressure gauge to the burner pressure test point
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Does the boiler ignite and run at correct maximum burner pressure of approx 11.7 mbar.
Note:
When pressure gauge is removed the pressure test point should be tightened and checked for gas tightness.