Unfortunately the plant was likely too weak or mostly dead when it was purchased, which is why it didn't leaf-out normally. (The buds it had on the stems were formed last year, and lay dormant for the winter. Normally, they absorb water to expand and push-out leaves in spring.) This implies the root system might have been in poor condition; root rot is one possibility, but the plant is too advanced in decline to tell from these symptoms alone. Since it will not recover, we recommend replacement, especially if the nursery provided a warranty period. (The nursery would not necessarily have been able to tell a live, dormant plant from a dead one that early in the season, so we're not implying that they were negligent in selling it.)

If you are open to it, we recommend that its replacement be another species of shrub/tree, because Rose-of-Sharon can be invasive; it has already appeared in natural areas in many Maryland counties. Some cultivars are supposed to be sterile (they won't produce viable seeds), but we don't know how reliable that trait is for every variety that claims sterility. Nurseries are still legally allowed to sell some invasive species, though with recent legislation in Maryland, that might be changing soon (the prohibited plant list hasn't been finalized by the Department of Agriculture yet).

Miri