If my failing memory hasnt left me completely dumb, I swear the 50-04 is actually dont with CAN communications, and that LON was the very short lived 50-03. Also when you say he replaced the button, do you mean the physical button? Or the expansion card behind the fixture? Or if it is CAN communication the HN card in the hoistway. Give me a few more details, and i will try and keep you outta the weeds.
