T4781FD - thanks for posting back. You said when you activate the GDO, it moves in the "close" direction. Have you let it continue to operate for a few seconds to see what it does? Does it then try to bounce back open, or does it stop its motor and the light starts blinking on & off rapidly/GDO makes loud clicking sound?
I have an old Craftsman unit at the house that's done this as well...if I let it keep traveling in the "close" direction, the unit reversed direction about 2 seconds after the door contacted the floor. The GDO pushed on the bracket and it looked like it wanted to bend, but then the circuitry sensed the door was closed/its path was obstructed and it reversed. It recently quit doing it after some drastic weather changes, and I can only troubeshoot it on the weekends...but I rarely open that door (2 car garage with 2 separate doors).
Letting the GDO operate a few seconds after the door contacts the floor may help determine if the door close limit contact has a broken wire (thanks, RPXLPX!), the magnet is malfunctioning, or if the circuitry inside the GDO is truly bad.
You and your neighbor's wall units must be wireless...my wall units are hardwired to the GDOs. It is possible the interference you both experienced with each other's units could have caused the circuitry in your GDO to fail, although your unit's door obstruction circuit should've kicked in as I described it above after 2 seconds or so of the GDO pushing the door closed after the door contacted the floor.
I'd recommend examining the door limit hardware up on the GDO track/rail...as RPXLPX stated, it could be a broken wire that's not visible from the floor, a contact that's shifted position, or something else easy to spot and fix. I'd also try the GDO again and see if it reverses direction if you let it go for a few seconds. If you see/hear something that concerns you (e.g., the bracket starting to bend out of shape, smoke from the unit, etc.), you can shut it off by hitting the remote button again. Or, you can position yourself on a ladder and unplug the unit from its outlet. Be sure to position the ladder so it's not in the path of the door as it opens. Let us know how you fare - regards! Jim D/West Point, VA