Are you saying the fireplace is also an open portal?
Have you tried a simple no-tool white light changing, or smudging the place (doing the whole house including the attic)?
More no-tool magick…
You could try closing the portal using visualisation to see it, and close ot any way you can think of (that part is symbolic to help your mind get hold of the energy, so it matters less what you see and more what you do)