Semi Off Topic: Can You Help Me Solve This Garage Door Opener Mystery?

This is only if you're bored, like a puzzle challenge or happen to know the answer from experience.

Here is the scenario. I acquired a storage unit at my condo complex that had an existing Chamberlain garage door opener with one remote and one wired switch. (Likely a consumer version). I happen to have some left over Linear wireless receivers and remotes that I installed at the same facility front entrance. Since I already had the linear remotes to get in the complex I wanted to install the extra Linear receiver in the storage unit and have it's dry contact output trigger the Chamberlain and be able to operate with just one remote. (I did the same thing at my home garage on an Overhead Door unit and it works like a champ).

The Chamberlain has a learn feature but it will not recognize a Linear remote. The remote that works with it is model number 950ESTD

I could not get the Chamberlain to respond to anything except their own button. I then took the button and wired it with a short test cable and it works fine. It connects with 2 wires and I assumed it was a dry contact

What I discovered is that it's sending power through the circuit as you can see from the illuminated button.

Here's the back of the button.

Here's a closeup of the model info. The button hooks into the red and white terminal blocks on the left.

What was strange was that I metered it and got BOTH 12 volt DC and about 24 Volt AC with minimal change when the button was depressed. (maybe a momentary drop of 1-2 volts). Shorting the button, Shorting the inputs on the terminal block does nothing. I'm perplexed. I'm pretty sure my Linear only has a dry contact output.

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