bad main board all else ok especially if light will not turn back on these sets turn on the backlights asap if not most likely the main board if led strips all ok!

if its a samsung with snap on covers sets were junk if standby flashes 2 times its a panel error unsnap 1 lvds cable at a time see if backlight stays on for about a minute if it does resnap tab back on main board to panel picture will probably come in a be great but if look closely may have a fine pixel line running through screen which causes set to go into shutdown!