Ugh - I think I have major damage. I have a Panasonic TH-50PX75U, which I got right at the end of 2007. Yesterday, it was working fine in the morning, but now I get no content through either HDMI input. I do get content coming in from an Xbox connected to one of the Component inputs - haven't checked the other component, the cable-in or other composites yet. We had a severe electrical storm yesterday afternoon, with a couple of strikes seemingly right on top of my house.
I have the system set up as: Scientific Atlanta cable box, roku, and DVD player connected via HDMI to a Panasonic VSX-1121 receiver, and on to the TV via HDMI. I also have an Xbox connected directly to the TV via component, and sometimes run a laptop to the TV on the second HDMI input for Youtube, etc. Currently, I get no picture or sound from the cable box, roku, or DVD player coming through the receiver, and no picture or sound from the laptop connected to the TV. There is a picture coming in from the Xbox connected via component.
Given that the there is no sound coming from the receiver when it's set for cable box input, but the cable box is responsive to channel change, etc, and there is no signal getting to the TV from any source connected via HDMI, could I have fried the entire chain of HDMI inputs and outputs?
Other observations - when the PC is connected to HDMI 2, and I use the TV remote to cycle through the TV inputs (cable TV, Video 1, Video 2, HDMI 1, HDMI 2, Component 1, Component 2), the picture on the PC screen clicks off then on when I leave or reset to HDMI 2. That tells me the TV and PC are talking over the HDMI connection, but there is no content being passed.
I'll continue to test with all the sources connected via component, to see if that works. Any suggestions for the best way to figure out where the problem lies?