Thank you SO MUCH. The design of this is so unintuitive to me. I had a hell of a time getting the battery back in-kept getting it almost all the way but it gets stuck on the compartment locking mechanism. Watching you slide it in I copied the exact angle you had and it slid in correctly! Also didn't realize you had to hold the test button to get it to work, so I had actually managed to replace the battery correctly twice but mistakenly thought I'd done it wrong because the test button wasn't sounding. Without this video I'd have wanted to huck the whole thing in the garbage.
Mine was chirping. It has both a battery and a connection prong to the ceiling (???). I started to put it up without the battery. It started chirping again so didn’t leave it up. But was it just recharging? I don’t know what the wire is for ..
We have a different First Alert with 9V battery that is much harder to get the battery in/out. Ours comes off of the wall/ceiling and then the wire connection part has to be popped out so we can work on the battery replacement. Try opening the battery compartment and pull it out until it doesn't want to come out farther without force. Under the battery, there is a rectangular tab that is bendable and can be pushed up into the bottom of the battery to help you get it out. Try to get the battery out without pulling the entire battery housing out. We did this once and pulled the entire battery compartment out and it was really hard getting it back in.
