I had this same issue. I had one alarm going off, and it had one of those 10 year batteries, and no off switch. I put it in a ziplock bag, and weighed it down in a pot of water. It continued to go off for hours. I sent the video to firstalert, they blamed dust, and told me I need to use compressed air about once a month to clean them out. F that, once a month??? I ditched them and got the google nests. They at least tell me which room is going to go off, and gives me a 10 second warning to silence them. You can silence them from any room, as long as you can reach them. Only had them go off randomly once and new batteries did fix it