I just read a post earlier from another site on Vizio would stay amber with stand by light and not turn white.I tried this and it worked on your main board locate the smd IC chip U26 and remove it and solder a 10K resistor on the last 2 bottom pads where the chip was,they will be across from each other,now my light goes from amber to white but still no light on screen,think it's Y sus.Bought a new board last week and logo wouldn't turn white so I must have bought a bad board because this fixed my old one.Hope this helps like it did for me.