Set Appliance State:

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

Observation:

Service mode reset procedure:
Rotate the CH temperature control to the spot position on the facia, then turn it to full and back to the spot quickly.
'SERV' should now disappear from the display.
Note.
If this process does not reset the service mode, try resetting it by turning the mains power off and then turn back on.