posted 5 months ago
Welcome to Permies!
I live in Zone 5B and have seen a variety of winter hardiness in rhododendrons depending on variety. Without seeing the plant, and even if I did see it, I'm more of an observe and adjust kind of guy. You might find that the plant recovers without any intervention, or perhaps you will get new shoots out of the ground to replace the damage that is already done. As long as the root ball overwintered, the rest of the plant will be fine.
This being the first year of overwintering, I would say that if the plant survives you don't have anything to worry about. It might need some future pruning, but I'd let it get established before worrying about that.