What I suspect is going on with your TV is either the backlight strips or the backlight driver circuitry on the power board has failed. If you have sound, but no picture... that's usually a sure sign of a backlight problem. The reason why this happens (sometimes right after the warranty expires), is because some manufacturers will "over-drive" the LED strips in the TV to make the picture look extra bright... at the cost of shortening the life of the LEDs. This video (click on the blue text to the right): https://www.youtube.com/watch?v=6hQOiN4-XPk describes how to check the backlight strips and the LED driver or power supply board(s) to help determine which may be the cause of the problem. If it's determined the LED driver board or the main power board is at fault, replacing those boards usually isn't too difficult and can be done by most TV repair shops or techs, or even by a consumer who is comfortable removing the back of the TV.
If the LED strips are involved (and often they are), it is a much more dire prognosis. The strips are usually replaceable, but it can be a labor-intensive project and there is the risk of damaging the panel, so most TV repair shops or technicians will not perform the repair. If you are interested in attempting the repair yourself, this video describes how to replace LED strips: https://www.youtube.com/watch?v=T2FboV-1PJg
The videos aren't necessarily specific to your model TV, but the information in them can be applied in general to any manufacturer or model. Most of the customers I talk to about this problem opt to replace the TV because of the amount of labor involved in replacing the backlight strips. That is generally what I recommend in your case, unless you enjoy tinkering.
If/When you replace the TV with a new one or repair this one, consider keeping the brightness of the new TV at or below 80% of the maximum brightness setting. For example, if the maximum brightness setting is "100", keep the setting at or below "80". This will help the LED backlights last longer.