The brown blotches appear to be scorch, which is due to environmental conditions like high heat and drought stress. You can snip off the damaged leaves for aesthetics if you want, but other than monitoring the plants for watering needs, there is little that can be done. For branches that have wilted and/or shed leaves, they are probably dying back, though we can't tell from the photos what caused the damage. A couple isolated stems collapsing might have a stem-boring insect larva in its base, but clusters of wilting/dying stems point to a root issue or infection like Southern Blight instead. If plants were being over-watered, root rot might have set in, which will also kill branches as the root system dies out. We also can't rule-out a different fungal disease called Botryosphaeria canker, which takes advantage of drought- and heat-stressed plants and infects branches, causing their death.

For now, you can prune off any wilted branches and see if the shrub produces new growth from the base. If so, it may recover on its own, though no fungicide or insecticide use is needed or warranted. If a shrub that has completely died back is removed, you can inspect the roots and soil surface for indications of either Southern Blight or root rot. When roots die from infection (root rot), the outer layer of the root will be mushy, darker in color, and pull off easily, leaving behind a stringy inner core. If roots are not dead, or died from other factors, they will take more force to break, will be firmer and paler in color, and tend to snap cleanly in two.

Miri