Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Remove two wires at connectors 7 and 8 of the X9 terminal block running to low voltage controls
Fit a wire link between connectors 7 and 8
Note:
If a link is already fitted skip this test and select
"Appliance still does not respond to CH demand"

WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Wait for 3 minute self-check to complete
and boiler to enter standby.
Apply CH demand.
Does appliance now respond to a CH demand?