Electronics like that do last, unless they don't want them to. Original Gameboys are still going. I expect most that have failed were destroyed by water or battery leakage or something.

It could be worse. I had a fake not-working plastic tamagotchi thingy that isn't in anyway a piece of electronic, or at least that's how I remembered it.

I remember somewhere around 1997 that our teacher built in a few small breaks during the day, so everyone who had one could run to the hallway to get the Tamagotchi from their coat pocket and feed it.

I still have my perfectly working V1! Although it's been sitting in a box for most of the past 25 years.

At a school near me: The staff thought that the Tamagotchi were a good educational toy and liked the idea of kids developing a sense of responsibility in taking care of them. OTOH, they could not tolerate the kids being interrupted during class in having to feed/play/etc. with their toys. The solution: Kids would surrender their Tamagotchi upon entering school to a teacher's aide who would be responsible for feeding/playing/etc. the Tamagotchis until the kids were dismissed for the day and would be returned their Tamagotchi.

I don't know if older models had this feature, but the one I have can be "paused" at any time by just pressing two of the buttons at once, so this sort of thing wasn't really a problem.

You can still buy Tamagotchi models from the 90s 'new in box', never been opened by human hands, and they almost always still work. The only issue is that the LR44 batteries can leak and corrode the motherboard. But depending on where the corrosion is, it can be cleaned up.

I've personally bought a bunch of unopened 90s Tamagotchis and they've all worked.

Where did you buy them from?