Suddenly my 1 month old smoke detector from Xiaomi Mijia Honeywell sounded, 5:30u in the morning. All the programmed lights in the house went on.
No smoke, no fire, nothing, false alarm.
I removed the battery from the smoke detector to kill the 80 dB siren and went back to bed.
A few days later, I was still getting a smoke warning when I reinstalled the battery, unable to reset the smoke condition.
Today I read about it’s a photoelectric smoke detector, not a radioactive thing . So I decided to open it, to clean the “light chamber” (dark room) where light reflected by the smoke illuminate the photoelectric cell.
First I removed the cover from the bottom. 3 clips around the bottom hold it together. In the middle is a round black button that can be lifted. Notice the arrows that mark the notches. I cleaned the light chamber and the cover with clean air.
With the white cover removed I noticed that the center of the white cover can be removed with a small lefthand twist. That gives access to the same light chamber cover.
After reassembling the false alarm is gone.
I will try it with some cigarette smoke to test it later on.