My garage was built in 1951, three years after the rest of the house; the garage-door opener is clearly newer than that, but it’s pretty much an antique just the same. After six years, the aftermarket remote control failed a new battery did not restore it to health and I ordered a new one, same brand, pretty much the same model.
Now if you remember these old village-smithy openers, the actual remote code is set by a bank full of DIP switches, extremely easy to work but presumably very difficult, or at least very expensive, to duplicate in miniature.
And if you remember old IDE drives, they came with a couple of jumpers, which you had to set with a pair of needle-nose pliers to identify which drive was which to the controller. A genuine pain in the neck, but generally you only had to do it once.
Now copy that pain, paste it to the size of a remote control for a garage-door opener, and multiply it past all understanding: there are fourteen jumpers, each of which can be set in one of two positions. I wound up having to move eight of them and discard two others to get it to work. A genuine pain in the neck. I hope I never have to do this again. Then again, this opener’s days are probably already numbered: the guy who works on my door has warned me that parts supplies have long since dried up. (We’re talking seriously obsolete here.)