I mentioned zone 11b. We're in Redondo Beach, less than a mile from the ocean. Always ocean breeze, frequent morning marine layer (May Grey, June Gloom). I don't think it's the car. That's mine and I'm usually parked there and the breeze blows right to left in this photo.

Actually I just doubkle checked. I'm 10b.

You covered all my issues. Sorry I can't be of more help. You might try asking at a reputable nursey.

Water it. Its not a wild Manzanita,its a garden plant and as such needs to be watered until the root system tells you "No need to water me" with abundant new growth. I just saw some in a Supermarket parking lot and with that twisty red trunk and branches really stood out.

Manzanitas are prone to some fungus pathogens that can cause branch dieback. I have thriving, established 'Big Sur' and 'Point Reyes' manzanitas that will occasionally have one here or there die. It is wise to sterilize your pruners after trimming. I cannot tell if that is what is going on with your plant, but it is something that can happen. Frequency may depend upon species/cultivar.

I never pruned it. I've reached out to the Theodore Payne nursery where I bought the plant but got no response. I have cut back the pride of madeira and gave it some water.

I meant if you choose to prune the dead branches off of the plant at some point, you should clean the pruners between cuts to help prevent spread in case that was the problem. I was not saying that prior pruning was the initial cause.