No picture or sound in my Panasonic TH-P42UT30A plasma TV?

"Paul, follow the trouble shooting algorithm attached to this answer. It does sound like your trouble is on the Main AV input board.

Hope this helps, good luck."

"TH - 50PF20, Power turned on (indicating green light, and a quick flash of power) But the buttons on the actual screen were locked .

We had to unlock it by pressing the volume up 4 times, then input 4 times, then press volume down 4 times and then selected Enter .

This unlocked the buttons on the TV it self and then we just selected the input."