It's not too hard to replace the blind nut.

Remove the old one first. Use a punch if you have one, a nail if you don't. A few taps with a hammer and the blind nut will pop right out.

The trick to replacing the nut is to use a length of music wire with a wheel collar on it. Put the blind nut on the wire and then thread the wire through the fuse and through the hole in the firewall. Pull through the firewall and with a little fiddling you can get the blind nut started in the hole. Pull on the wire with pliers to set it just a little. Remove the wire.

Now for the tricky part. With a light touch try to thread a bolt with a fender washer into the blind nut. Don't push or you'll pop the blind nut out and you'll have to start over. When you get it started, tighten the bolt down and it'll seat the blind nut.

Dave