Break off a twig and see if it is still alive. Cut off what is dead.

Sounds like winter freeze damage. As stated all you can do is cut out the dead and go with the new shoots. There will only be new leaves on new growth. Leaves aren't going to pop up on old wood without new growth.

We have one 3rd year plant here that looks dubious. Low winter temp was +16F.

Just give the tree some time and be patient. Not all poms break dormancy at the same time. Don't start pruning, until after the tree has started to grow and you know what's dead and what isn't.

My pomegranates did the same thing. They fully leafed out then we had a late freeze and most of the top us dead now. Though they are putting a lot of growth from the bottom right now.