I have 2 of them. I took down the wrong one and dismantled it...and the beeping kept on going. So, I try to take down the 2nd one...only the wires won't come unplugged from the ceiling. So, I balance precariously on my ladder and manage to get the battery out of it. I go to get in bed and then....CHIRP. I was absolutely livid.
I finally had to pry the adapter/wires thing out of the back of it with a butter knife.
Now hopefully my apt doesn't catch on fire until I get around to calling maintenance.