Based on the symptom most probably it is a problem of the backlight. In order to confirm this, you need to do the torch (flashlight) test. In the darkroom try to see the screen with torchlight if you are able to ‘see' the faint video, this could be the problem of the backlight. Backlight fails either due to power supply failure or one or more LED damaged in one or more strip. Replacing backlight needs the help of a professional if you are not sure what you are doing. If you don't see the faint video, this could be the problem of the t-con board. Replacing the t-con board is relatively easy.
Most of the smart TV'S comes with blinking (LED) codes, but meaning of these blinking codes differs from manufacturers to manufacturers. Just Google it (manufacturer / brand / model) and you may find the problem. Most probably this problem is related to power supply (bulged capacitor).