It should recover if, 1. You keep it away from your friend and 2. Nothing but water for awhile and that only as needed.
Don't try and fix it or love it to death.
My kid did the same thing, using SS mix instead of my seed starter mix. Really badly burnt and we both wanted to pull it up. But, it was outside and not in the way so it was left to see what happened. Did nothing but water (left it in the SS), and it is now a very nice bush.
It's not going to cost anything to let it go and you can start another seed if you feel the need. Won't be out any more time than if you did toss it.
See what happens and learn something.
Wet