You could take some plastic from the inside structure of the case, something not crucial to the integrity of the case, snip a bit, then "weld" it into the burn with a soldering iron after cleaning up the area with a dremel. Then, you sand it down smooth.
To truly get the texture back, you'd need something like a sand blaster though.
It's probably not worth it, but I've repaired some cases this way. It's not the easiest way about things.
I've also used this stuff to fill gouges.
https://www.amazon.com/Plast-aid-80400- ... B004DFHSM6
It will bond with most plastics.
It can be colored with acrylic paint so you can try to do a color match. Still, retexturing is the biggest PITA when it comes to repairing a case or anything with texture.