Chosen Solution
Vizio tv D55un-e1 Watching tv one day and the next day it went out and I waited one day and tried to see if it would come back on and it didn’t I thought it was completely black until I used a flashlight and could use the remote to still do things.
You are correct with the troubleshooting, that the backlight is out. That is most likely caused by a bad inverter board. If you are electronically technical you may be able to troubleshoot and fix it on a component level. Otherwise, a board replacement is necessary.
