Hole where fire alarm was continues to chirp

I am going crazy. I have 4 fire alarms (3 in bedroom and 1 in hallway). One day the hallway alarm started chirping and battery changes weren’t fixing it.

We decided to pull it down and it still continues to chirp BUT FROM THE HOLE LEFT BEHIND.

  1. The bedroom alarms are not chirping (you can tell when you shut the door it’s not that alarm).
  2. I’ve turned the breaker off to the fire alarms (I have an unwired fire alarm for safety) and it continues to chirp.
  3. Kidde brand, about 7-8 years old hardwired system. They all seem to communicate to each other. I have changed all the batteries once so far (so that’s why I am doubting there’s a secret one in the ceiling). It did briefly stop chirping at one point but it has since started again.

How does it continue to chirp? What is still chirping? I’ve turned off power - what. Is. chirping. lol. I feel insane lol. Thanks for any help in advance!

Is there an attic, crawlspace, or similar area in your house? If so, there’s likely another smoke alarm hiding in there.

Yes there is - man I was hoping the mount just chirped lol. I have no idea how and who is going to be able to get up there. Thanks randomperson!