Set Appliance State:

Mains Power Off
Ensure the appliance is cool
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Observation:

Attempt to reset the appliance, does the
appliance reset or does 04 code remain?
Note:
Switching the mains power off and back on
will not reset a lockout on this boiler.
BOILER RESETS - CONTINUE FAULT FINDING THROUGH MODEL
04 FAULT CODE STILL PRESENT