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Get the clean shower drain body and place it into the drain. Use your hands to twist the drain body clockwise and tighten it as much as you can. When you can't screw the drain body any more, use a hammer and a screwdriver again to further twist the drain body into place. Fitting the drain body causes the caulk to spread slightly, so it's important to remove this excess caulk before it dries. Get 2-3 sheets of regular kitchen paper towels and use these to remove any excess caulk. It's best to wipe around the whole opening of the shower drain with the paper towels to ensure that you don't miss any caulk that has oozed out. You can also use an old rag to wipe away the excess caulk. Push the strainer back onto the drain body and make sure that it sits flat. You may need to hit it lightly with a hammer to ensure that it's in place. When the strainer is in the right place, use a screwdriver to put the screws back in. Make sure that you tighten the screws well. It's important for the new caulk to cure and set properly before you use the shower again, as otherwise, this might damage the caulk. Read the label of the caulk carefully to check how long your specific product takes to dry.
Screw the drain body back on. Wipe the caulk away off the edges with a paper towel. Screw the shower strainer back on to the drain body. Let the new caulk cure for approximately 24 hours.