I am very sorry to tell you but it is very likely that it is dead. Junipers have a very delayed effect when it comes to death. Meaning, most likely, it wasn't the rain that did it in. In fact, it may have been something that happened even before it came into your care. You could let it go and see if it shows any signs of life but once it goes brittle and brown like that it's not a good sign. It is possible that it might try to push new buds. Without knowing more it's speculating really. Again, very sorry about the tree but happy birthday all the same!