Hi, Most of it does appear to be dead, especially since the other ones are so much farther along.  You could confirm that by cutting it back, starting at the outer and top branches and going in to the center, making sure at each new cut that it's actually dead and stopping if it's alive at that point.  The dead wood would be dry and brittle.
Too bad and also odd because the others look fine.
Let me know if you have any other questions.