TV turns on for about 5 seconds then shuts off.

Model number? Does the standby light blink any number of times? If so, how many times does it blink? Are you able to turn the TV back on immediately?

Please provide more details. A TV shutting off shortly after turning it on could be just about anything, and without knowing what kind of TV it is impossible for us to help you. Panasonic makes all kinds of TVs including CRT, LCD, Plasma, etc.