A black screen can be caused by a number of problems:
# Defective LED or strip of LEDs that provide the “back light” for the picture. This can be confirmed by using a a flashlight. Point the light at an angle to the screen (with it on) and you should see a shadow of the picture on the screen. This means that the panel is working and the backlight is not.
# If the flashlight test fails, then it is possible that the “T-Con” board or the processing of the image is not working properly. This may be a separate board or part of the main board.
# It is also possible that the power supply for the backlight has failed.
# There is a slight possibility that the panel itself has failed too although this is rare.
Reset ALL components by unplugging them for 5 minutes including the TV. -Be sure all COAX CABLES and HDMI CABLES are tight and properly connected. - If you CAN pull up the TV MENU when you have the black screen, update your TV's firmware to be sure your TV is up to date and rule out the TV as the problem.