Dogwood looks bad
The shrub might be suffering from transplant shock. It usually takes a while for newly planted stock to adjust to the change. Some plants recover from transplant shock. Others do not. In this case we recommend proper care and watchful waiting.
Please bring the shrub's condition to the vendor's attention. Reliable companies usually guarantee the viability of perennial plants for a year or more after the purchase date.
Go here to learn about transplant shock and how to deal with it: