I think my elm tree was struck by lightening. I came home from work to find my sprinkler system controller blown off the wall. It appeared that lightening had struck the tree, gone through the root to the sprinkler system wiring and then blew the controller off the wall. The tree still looks good, except for minor-looking bark damage to one large root flare. Will my tree die? Should I do the sick tree treatment, just to nurture it? Any other advice?

The STT is definitely in oder. If the damage was external on the bark primarily, your tree will probably be fine.