I need help (Flickering screen)

@edumoratinos that looks like a bad backlight. A simple check for that would be to darken the room and turn the TV on. Then use a flashlight and angle the light at the screen on different areas. See if you can make out shadows or shapes during the times where it turns black. If you do, then it is your backlight that has failed.

If you do not see anything, unplug your set and remove the back cover. Then visually check the boards for any obvious damaged components. Check all the wiring and unplug the wires and plug them back in, make sure they are properly seated. Post some images of all of your boards with your question. Use this guide Adicionar imagens a uma pergunta já existente for that so we can see what you see. It is possible that this is either a power board or a T-con board issue.