He is wrong, there is stuff in/on the old one that can break. No software. But springs, levers, and such can/will break.
Electric ones can break if they fall. They are either on low power wiring from the hvac or have a 9v battery powering them. The biggest points of failure are any kind of button you press, wearing that out to the point it doesn’t register you pressing it anymore. If on hvac wiring for power a power surge might damage it.
He is a licensed electrical engineer with years of experience and he is not wrong. There is no button to press, just a lever to move and he examined the insides and pronounced them in perfect order and they would stay that way. All he did was blow out a bit of dust in there. If this man says it, one can believe it.