I have a 4 year old VIZIO XVT473SV that now has NO sound, NO video, NO startup "V" screen, essentially non responsive and dead.
The VIZIO light on front blinks orange and white for a few minutes and when I turn it on the light turns white. That is all that tells me that the TV is "on"

Called VIZIO who told me to hold power on TV to drain and reset to no avail.

I have spent a few hours reading as much as I can find in this. Most posts speak of no video but audio and backlight or some combination of this. Mine has NOTHING.

I took off the back. Saw an LG panel and board (made me more upset it died). When I turned it on, a BLUE LED on a board in the far left on the back lit continuously. I also noticed the red light in the optical in was lit. NO backlight.

Even with a flashlight on the screen, there is no video.

This is where my expertise ends. I have zero electrical knowledge, have no testers and cannot check resistance or voltages.

My question to the forum is: with these symptoms, what is the most likely cause?
ITI (the VOZIO repair contractor) charges $150 to walk in the door and with a new similar TV costing $600 I am not keen on spending $350-400 to fix this.

Any contributory responses will be appreciated.

THANKS!!