Thanks for the reply.
There is a failure on the power supply board inside the TV. Commonly the capacitors on this board will receive a surge and then fail. They can sometimes be visually verified by removing the rear of the set and inspecting them for bulges or leaking fluid at the top or the base of the caps. This is the most common mode of failure for these sets. The problem could also be a cracked solder joint, or failed IC regulator, in which case it would be more cost effective to replace the board itself. The link to the power supply board for your TV is below:
Unfortunately there is no sequence of buttons or reset you can perform to get the set working again.
If you're not comfortable doing this yourself, a Tech will charge around $225 parts and labor for this TV. In this case I would suggest using the link below to locate a technician in your area: