I have a 98 c230 and the door locks and rear headrests do not work, trunk release also not working. Keys not unlocking and locking doors and trunk. Mechanical key is only hope... ignition works fine. Mercedes said it is most likely central locking pump... I checked and it does smell like it burnt. I bought a used one...my question is what will I have to do to get this one to work.... anyone with any insight or input.