Hello , my name is Jack Perhaps I can help you with this problem but first i would have a few questions;
About that message , "The DVI/HDMI output is blocked" , can you confirm that it is exactly what it says ?
What I mean is that it is the word "output" and not "input"
How about the cable box remote, does it have a "exit" button ?
What I typed is exactly what we are seeing on the screen.
O.k then your tv does not have a HDMI output , so it would seem rather strange that this message would come from the tv.
While this message is on the screen, if you turn off the cable box , does the message stay or disappear ?
Can you see my reply above ?
THe cable remote has EXIT on it. When I turn off the cable box, the message disappears and the screen is black.
O.k then , no matter what the cable company says , right now it does look like a cable box problem.
Pehaps your cable box may need to be rebooted.Pull the cable box`s power cord off the wall outlet (cable box only) for a couple of minutes.In the mean time turn off the tv and turn it back on only after you plug back the cable box power cord.Note that it may take a couple of minutes for the cable box to reboot after you plug it back ,just give it time.
Let me know how it goes.
Hope this help and please take the time to rate my answer if that does the trick , otherwise do not rate at all , just let me know and we`ll see what can be done.Note that you can reach me here at any time after rating if you have questions.
We are up and running. All we did was move the cable box and the picture came on the TV. This is crazy because the cable box is never touched or unplugged from the wall. At any rate, we now have a picture on the TV.
O.k then it is possible that the HDMI cable had bad contacts.
In any case that message was coming from the cable box I`m sure.
If it happens again then try to pull the HDMI cable out and back in at both ends and if the problem persevere , have the cable company replace the box.
Thank you and please take the time to rate my answer positively as it is the only way i get credited for my time helping you.