回复：怎么证明the opener 的circuit is not also Too old.

First, we don't need to confrim/verify everything in this world.  You have many more important things to spend time on in your life;

Second, a new one will work and the one LZ has is not working anymore.  The most likely reason the old one is not working is because it's too old and the electronic parts aged over time.  For $20 you solved problem and you don't want to spend time trying to figure out everything.  Even after you solved the mistery, if you can, it's highly likely that my guess is right and it does not make any difference in terms of outcomes - replacing the remote.  Also, my guess is based on my experience;

Third, if you think you can get onto moon by yourself, I believe you aslo.