I’ve abused smoke detectors. Hmm where to begin?
I put 80 volts DC through a First Alert 83R. Some resistor(s) started emitting blue smoke on the board below the horn, then the horn went silent after chirping once.
I have smashed a smoke alarm with a hammer before. It was dead anyways.
I have also dunked a smoke alarm in a bucket of water. NOT an AC alarm. It squeaked strangely then went silent. The LED was not blinking but glowed steadily and dimly. When I took it out, the horn was squealing just a tiny bit. I blew most of the water off and it chirped back to life. But, ever since then it goes off as long as it gets power.