I bought a Franklinia tree at Bartram's Garden spring plant sale it has been doing well up until the last two weeks.
Franklinia are sometimes difficult to transplant because of their sparsely fibrous root system however young container grown or balled and burlapped trees sometimes do better. They require moist, acid, well-drained soil with ample organic matter. It sounds as if you may have a combination of extreme weather conditions this summer and lack of good drainage from insufficient organic matter in the soil. Consider carefully excavating and preparing ideal soil conditions as poorly drained soils often prove lethal to this tree.