Network Garage Door opener/ how does the switch work
Do you have a button switch on the wall to open - close? There are usually two wires going to that. I don't think it will hurt to short those wires momentarily to test it. If it did, Lift Master would get a lot of returns because I'm certain many people have shorted the wired pair upon installation. My Craftsman has two wires going to a multiple switch panel. I can open - close the door, turn on-off the opener light, and lock the remote controls. These functions are controlled by adding a resistance to the wired pair. each control has a different resistance. The open-close is just a short. the unit remembers what direction it went the time before. IE: if you short once to open the door, then short again will close the door.