It looks like it's still alive and it'll make a new main branch eventually. You'll need to prune it properly if you want it to look like a tree again, but it'll probably take a year or two. I would probably remove that stake and the tape holding it on there. That tape can cause issues if it's left on too long. If it needs support, you'll want to add stakes that are away from the tree and use a tree tie or something like that.

Just out of curiosity, how did the sprinkler system kill the top half?

The sprinkler system stopped working while I was out of town last summer. I thought the whole tree had died during that time, but turns out there is new growth from the bottom, but the top is certainly dead

This method will produce some sort of tree, but it's a lot of work.

1 - REMOVE that stake ... it's not doing any good now, and would have killed the tree by strangling it if the sprinkler had not killed it. Stakes like that are protection during shipping and planting, not intended to be left on the tree like a splint ot corset.

2 - Cut the old trunk out to just above the strongest of the shoots. This will be your new "trunk".

3 - Prune off all the other shoots and let the new trunk develop. Do not prune anything from this new trunk for a while. Do not stake it, do not fertilize it and do not overwater it.

4 - If any other shoots develop, remove them promptly.

5 - When the new trunk is about 8 to 10 feet high, start slowly removing the lowest branches to make it look like the old tree.

It will take several years and vigilant pruning because when the top dies like that, the plant wants to become a bush.

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Faster method - dig out the bushy mess and plant a new well-shaped tree.

And learn how to properly stake a tree.

More information on staking trees.

https://amwua.wordpress.com/2016/04/25/2417/

http://www.amwua.org/landscape/landscape_staking.html