We recently had a serviceberry-autumn brilliance planted (June). It was past its flowering stage but immediately the leaves began to all off. It was well watered in the beginning. It is now turning orange and the leaves are falling rapidly- other serviceberries in the neighborhood are still green and leafy. It seems too early to be displaying these autumn colors and to be losing leaves- is this normal for the first season?
Too soon to worry -- your serviceberry, from what info you gave, is stressed and is going dormant. You set it out at the onset of a hot summer. Keep it from drying out, tho. Dried out dead leaves would mean it's dead.