Locate the existing television cable input and then choose a location above the fireplace that is closest to the side where the input is located. Turn on a stud finder and slide it over the location to ensure no studs are behind it.
Hold a mud ring retro box up to the wall location and trace around it with a pencil. Cut out the wall area using a drywall saw. If the area is brick or masonry, use a diamond-tipped masonry saw to penetrate the wall cavity. Insert a mud ring retro box into the opening and secure it by inserting the provided screws in the top and the bottom.
Move out horizontally from the opening until you are directly over the location of the existing cable input. Cut a 3-inch-by-5-inch hole in the location using the drywall saw.
Kneel down and remove the cover plate screws from the existing input and pull the cover away from the wall.
Tie a heavy object to the bottom of a fish tape wire. Insert the end of a fish tape wire through the top hole and drop it down until you see it emerge in the bottom hole. Clamp the end around the television cable, then wind the fish tape tool until it emerges from the top opening.
Detach the fish tape, but tape the end of the cable to the wall so it does not fall back inside the hole.
Move to the opening above the fireplace and insert the fish tape through it. Thread it sideways until you see it emerge from the opening where the cable is. Clamp it around the cable and remove the tape from the wall. Wind the fish tape handle to thread the cable through the wall to the opening above the fireplace.
Detach the fish tape and pull the cable through the mud ring box. Insert a cover on the box using the provided screws.
Proceed to hang the flat screen television above the fireplace, following the mount instructions. Then patch the wall holes by replacing the cutouts with drywall tape. Apply joint compound over the tape and sand it smooth once it's dry using fine-grit sandpaper. Paint the wall as you desire.