Just changed battery in 2nd remote
 

And it remains non-functional. When pressing a button, the orange light on the fob lights up but it’s not recognized by the car.

as noted, this is fob #2 not the primary which works as designed.

am I missing a step? Cr2023...

Update
 

Service Mgr - 90 miles away, mind you - says it needs reprogramming. But he said I could take it to my local Honda store. I guess paying for 1/2 hour at Honda is less $ than 180 miles round trip. I’m planning to use them for oil changes anyway. And I’ve - or my kids - have had four prior Honda’s, so they sort of know me.

Why hey does it need programming? Who knows. I am hoping this is all accurate.

Reprogram. All good. Local Honda shop, just under $35.

Did you ask or find out why it needed to be reprogrammed?

Afraid I have no idea.

somewhere in your area is a MDX owner with the same problem, wondering why his/hers stopped working.

Merlin - what do you mean?

somewhere in your travels that remote got swapped with another. Valet, dealer etc. The key comes out and all the remote bodies look alike. Someone picked up yours by mistake and you got theirs. Just a hunch. If your wife for example dropped the car off for service, and the two of you picked it up, you would not have noticed the problem until she went to use her remote.