Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do what I can to provide the right answer to your question.
Offhand it sounds as if the control box is in a state of shock, 'locked up', and a reset of the control box might be the right thing to try.
(But I confess I don't know a lot about Greyfox intercoms, and because of that and since you requested Carl, I have Opted Out, opening the case up again to other Experts.)