I posted a similar thread to this about HDMI connectors I believe frequent plugging and unplugging has caused some nearby tracks/solder joints to crack producing problems. This was on my LED widescreen TV, the symptoms were sparkles on the screen, like fine glitter had been scattered on it.
This might be similar to what you might see if the cable was of too low quality and you were getting digital errors in the signal, I can be pretty sure it was not the
cable because it works fine in less frequently used connectors. It is hard to see what else has caused the problem other than the fact I was plugging and unplugging with
the power on, but I would not expect that to cause the symptoms seen, more likely a failure of the system which did happen yesterday.
Anyway my TV is dead as far as displaying a picture is concerned, it will not respond to the remote (although hard to tell with a black screen) although some
of the buttons bleep when pressed but that might be a locally produced sound.
I'm gonna have to take it back to the shop for a refund, it's less than 4 months old so hopefully they will be willing to give me my money back or and other TV. (touch wood)