If I were you after removing all the dead flesh that you find a shady place in your tank to let it sit for a while (maybe 2 months) I had an LPS recover from certain death once, from 100% skeleton to full recovery in about 6 months or less. Seriously thought it was dead but there must have been something inside the skeleton in the mouth area that was still alive.
Maybe a light iodine/tank water dip before forgetting about it?
Sorry to see this happen
And what Ryan said ^^^ that brain in the background looks noiiice