Sounds like it is a "hardwired" unit w/o battery. The surge or spike might have caused damage to the unit. If there is a test button, press for a few seconds to reset it. Hope that helps, otherwise you will have to replace. Turn off the breaker when you do.

If it's got it's own battery, as most of them do, it is not affected by any fluctuations on the household power.

More likely it has a flat battery, or even low battery warning beep.

Yes, that tis the dead battery "beep"

low battery indicator. mine has a 9 volt battery.

So earlier this morning (10AM) my power flashed for like, a second. One of my smoke detectors started beeping around 2PM/twenty minutes ago.It's just a single beep every minute or so. Is it beeping cause of the power surge that happened? I don't understand much about this type of stuff, so I'm really confused.