This thing! It started beeping after I'd gone to sleep last night. I wish I had just put in some earplugs and left it until morning when my brain was working better, but my brain wasn't working, so I made the decision to (try) to sort it out.
We've lived here a year. I haven't paid huge attention to where the smoke alarms are. This one was at the top of the stairs, in an awkward position to access. Also it's mains powered, with a backup battery and it starts beeping when that battery starts to fail. So first I had to go down to the basement to turn off the power for the circuit they run on. Then find the steps and a flat head screwdriver so that I can climb up and get the unit off the ceiling. Then pop a new battery in and it should be all OK.
Except it turns out that it wasn't this one that was having a problem. Even though I did everything right, there's also another unit at the other end of the landing, which I didn't know existed. And at that time of night when I'm all over the place and just want to go to sleep, I couldn't quite believe what my ears were telling me, which was the beeping was coming from a few yards away.
So I went back to bed, woke up at dawn with the beeping still going and only then realised that I'd changed the battery in the wrong unit.
All the while, my wife is trying to tell me that there's a story in Friends where this happens and they solve it by hitting it with a baseball bat or something.
A lot of additions to the household todo list today - including sourcing smoke alarms that don't mess with my sleep (unless they're doing what they're there for, and the house is on fire!)