Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble, John.
To clarify, this is a paid support site, and comcast/samsung do not provide this type of support for free either.
It is actually unlikely that this is only a box issue, based on your description so far.
Initially, unplug power to your comcast box for 60 seconds to reboot it.
If no change, I need to know if you can see the samsung on screen setup or input menus, and what the full model number of the tv is, as well as if you can use the tv with another device successfully (dvd, apps, etc).