Slight hint: I may have inadvertently tried to pair up an AC adapter or breadboard with similar power rating with the remote, which showed the same behavior, prior to use the designated watch battery. Not sure if that would've done anything, but saw this behavior on one other device...matching an AC adapter's power ratings. Do they always have to be that exact?
Batteries* have a thing called ESR (Equivalent Series Resistance) which causes them to act like a battery plus
a resistor. Draw a circuit with a battery, now add an extra resistor. That's ESR.
ESR means actual voltage you see from a battery will be less than the amount printed on the label. Button batteries have a very high ESR. A 3V button battery might appear to be a 2V battery if you connect a load to it.
AC adapters don't have this effect. Connecting a 3V adapter to a place where a high-ESR 3V battery normally goes could overvolt a device and kill it.
(*) Yes, all devices have ESR, but outside of batteries it's usually too small to notice.