What I'm stating is that the Scan driver boards, or the Power supply, or even the main board could be the problem. The person who sold you the TV would have absolutely NO way of knowing unless he measured voltages with a meter on the outputs of the power supply board to determine if:
A) The Scan Driver board(s) are shot.
B) The Mainboard is shorted.
C) The Power supply is not outputting it's spec'd voltages.
I could tell you that the Power Supply board is around $100, and the other boards cost more. Here is a link to the boards from Vizio, but again, without testing them inside your TV with it powered up, you would be shooting in the dark as far as replacement,
Again, the best course of action at this point is to locate a Tech at the link below:
If you need further assistance, let me know.