OOOps.. like what? I have seen things that my response was 'I'm not doin that!!' Please post when you see something.
you say the chimney cap was blown off. did you recover it and reinstall or replace it?
regarding sealing the fireplace with something reversible, a friend of mine used a piece of that rigid insulating foam to seal off the top of his fireplace under the damper. i think 1.5" thick and then sealed the edges with metallic HVAC tape. he painted it the foam black prior to installing it.
his was a masonry fireplace so not sure if it would be too visible with your factory box.
insurance company paid for replacement It fell about25 feet onto concrete, it was a tin can thing
I'll see if I can epoxy magnets in there to hold it in place.
There is a lip on the screen which is big enough and I'm sure there is room above it. Will not be able to see it unless eyes are at about 18" from the floor. Being flat black ( I got the paint to spray inside furnace registers to make that construction invisible) and a flat black screen in front of the fireplace will make that installation invisible also.