I’m no expert, just relying on experience. I would pick several trees and start pruning back branches until I found green wood. Likely the smaller branches’ cambium later and sapwood were destroyed. If you leave these on the tree, they will contribute to drying out any surviving wood and weaken any living parts.
I suspect the roots and lower trunk may still be viable. Continue pruning back to old growth and, hopefully, green wood. You will lose several years’ worth of branch growth, but may yet save the tree.
Hope this helps. Breaks my heart to see this loss.