I received my XB6-A today and all that was in the box is the XB6-A, no instructions, no power cord, no idea what else may be missing. Not likely to get used as delivered. Great service Comcast! once again.
The instructions and all the cords are in the base of the box in a separate compartment. It's not clearly marked, but unfold the bottom part. I know this because I thought the same as you when I got my XB6.