Dirt,
Your original description reminds me of years back when Janus Edges were then common but failing at an unusually high rate. We had this readable gadget for each TX LED. If signal strength didn’t reach a specific threshold, replace the set. But the detect LED did extinguish like the edge saw the input, but doors would close anyway.
However, that was 20 years ago.
I can assume this unit used to function as it should, but now there’s this problem.
Might it be something as goofy as the Front Panel Door Disconnect Switch?
You see DET go high, but that’s from the TOCC? Is there an DET module in the controller? Or wires landed on DET terminal strip on the backside of the controller?
Most likely you’ve covered most bases by now, but I’m just thinking out loud here.
