well, it's going to be a pain in the butt and a 'nit-picking- project but....
take out those two squares and replace them...
if you don't want to cut into the muslin (check real close to see if IT got burned too).... just replacing those two squares should do it...
I was working on a quilt top and finally realized that I had a square in a block turned the wrong way! :shock: so had to take it out, turn it, then stitch it back in...
it's painstaking but doable....