Have a duplex job that the mechanic is indicating trouble with only the top floor hall call. sometimes the hall light is on but no cars respond, he says he resets it and it will work, now he says that the button when pressed goes on then comes off, and nothing responds until he resets it. I'm not to familiar with this units hall call boards, sounds like a board problem to me, as all other floors are working is there any special programming involved in replacing this hall board, or is it just plug and play. any help is appreciated