Contacted Nortek and got alternate answers the beeping after utility power-outage was designed in behavior, then rep later said it indicated device failure I believe the former case.
I’ve found Owner(me) unplugging then replugging stops the beeping. Wondering WHY Nortek would design such behavior? Just sloppy design? There’s a notion that the Door tilt sensor needs to resend it’s state after utility outage. That kinda makes sense, except that pushing the physical door switch should force the sensor to resend (but in practice, that usually doesn’t resolve the beeping).
Exposure here is if Owner isn’t around to replug, beeping will keep up the neighbors forever. Or if someone is RELYING on the beeping GD00Z to get into the door, their thwarted.