Hi jgs,
If it's only on the surfice and turned a lighter shade of brown the it should survive the damage okay.
If it's gone through to bare wood,obviously the damage is more serious but may in time heal over as the cambrium tisue grows to seal off the wound.
I would recomend that the wound is left open rather than try to cover it with anything as this could encourage fugi by providing the kind of conditions in which it thrives.
You still have 2" of sound bark so theirs a good chance it will heal. Good Luck. Tbird+