or chanel of a big super brand, that a 15,16,17,18,19 year old has been the face of?
You can either try and open the entire smoke detector by unscrewing it, or the easier method would be to get a flathead screwdriver with a very small head and pry the case open. If that doesn't work, or if you don't have a flathead screwdriver, get any flat, thin, but strong random objects from around the house to see if they work. In the end I'm guessing it will just be brute force that gets it open.
Go look at any fire hydrant on the street. Usually there will be a round steel valve box cover, perhaps six feet from the hydrant. That cover will be between the hydrant and the main. If you can find another hydrant on the opposite side of the street, it will have the same arrangement. Mark a point the same distance from the opposite side of the street. The main may be half way between the point and the cover. A more sure way is to hire an underground utility contractor to find it. There are instruments that can find it
