Hi. I'm Steve. I'm sorry to hear about your TV. I will try my best to give you a precise and accurate answer.
I can help you but I need to know the full model number. Panasonic are on their umpteenth generation of Plasma sets. I need to know which one you have.
The problem is with one of 4 boards in the TV namely: SC, SD, SU and P.
There is a procedure to determine which one it is. You would need to remove the back from the TV and you would need a multimeter.
Otherwise, I can only tell you that you are looking at a repair bill in the $300 and up range. Keep in mind that a new 40" TV is around $325 at Walmart.
Let me know if you want to continue.
Just ask if you need more help on this issue. I will be here.
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Thanks very much.