While you wait for answers, we may have found some information which could help you.
Click here for Boiler Heating Pcb Board
Siemens RDJ10RF thermostat problem?
Remove boiler cover?
How do i stop the time from flashing on the Siemens RDJ100RF?
Greenstar 24Ri boiler, fast flashing - can I reset?
Remove cover off gas boiler?
One radiator in a bedroom is always cold?