We have Comcast Internet and basic cable TV. We have a line to our kitchen TV (without a box) and it gets cable. We have an old TV downstairs, so I picked up a cable box from Comcast. I connected it and it would just show the message 'initializing operating system' and never anything more. I went through all of this with a Comcast rep on the Internet and she suggested a new box.
I went to the Comcast store and exchanged the box, brought it back, followed the instructions and activated online. This one says it is booting, then just a blank screen on the TV and then no lights on the cable box. I just spoke with a rep. who suggested I connect it before the splitter, which I did, but no difference. I have waited 30 -45 minutes, unplugged it and then reconnected and waited more. Did another activation, but so far nothing.
As a follow-up. Comcast could not figure out the problem and I was not willing to pay to have a tech come out (as they said I would probably have to pay - if the issue was my fault). I decided it was not worth it and cancelled the TV part of my cable and now just have Internet. Comcast tech support needs some work.