Japanese maple lost all leaves in summer heat

I live in Seattle. I have had a Japanese maple for 3 yrs. This is the 3rd. It thrived until this summer. I watered it less because I thought it had established itself. But we had a period of no rain for 10 days and one of them reached 91 degrees. Within a day or two all the leaves shriveled and died.

I've attached two pictures of it. Do you think it is dead? Or dormant? If it is alive but dormant, should I continue watering through the summer? Or stop? Should I prune dead branches or leave them as is? The outer branches are quite brittle and break off easily, which makes me fear the whole tree may be dead

Hi Richards1052,
Sorry to hear about your troubled maple tree. I hope you are still watering it. Yes, it sounds like it lost all it's leaves because of heat and little water but that doesn't mean that it's dead. They don't usually die so quickly. If you want to be sure you can carefully dig down into it's higher root zone. If all those fine roots are still soft but strong then it's still alive and will probably come back next spring like nothing ever happened. As long as you keep it watered. But Japanese Maples are rather finicky and need to be pampered. This website might help you. They know a lot more about Japanese Maples than I do. Lots of luck to you.
https://www.thetreecenter.com/summer-care-of-japanese-maple/