Mini cable box

I have one tv with the  contour box and three with the mini boxes.  One of the mini boxes does not seem to be working.  I have unplugged and plugged it back in but the light still does not come on.  My other boxes are working fine.  I have disconnected the box from power and tv and intend to take it to the Cox office next week.  I did try the box on one of the other tvs.