We agree that it looks like there is a small population of scale (maybe Japanese Maple Scale, but it's hard to tell) present, but they did not do this degree of damage. It's hard to determine what caused the collapse of the plant, but it may have been a root infection or something infecting above-ground, like a canker disease. Sometimes plant stress or injury (like root damage from transplanting, though some is to be expected and usually isn't a problem) predisposes plants to infection. We suggest the shrub be removed, and you can try a replacement. Chokeberries are generally pretty adaptable plants once they get established, but perhaps the shrub was too dry or too wet at some point, or maybe it arrived with an infection already beginning that was asymptomatic enough that the nursery didn't detect it.

Miri