Hi. I'm Steve. I'm sorry to hear about your TV. I will try my best to give you a precise and accurate answer.
Are you able to pull up any kind of menu on the TV? Grab the Samsung remote and press MENU.
There's no picture at all during the "dark" periods, including menu or input select.
This set has an LED light engine so you do not have a lamp.I would probably suspect the LED drivers.
Is this something you want to repair yourself? Can you troubleshoot electronics?
Or are you just looking for a repair cost and a recommendation of a good shop in your area?
Let me know how you want to proceed.