I can hear the sound but there is no picture

ninavillaa  shine a flashlight at an angle against the screen while you are hearing the sound of an active channel. Let us know if you can make out shapes and silhouettes. If so it is a backlight issue that could come from a bad power board or a bad backlight array (common with Vizio) If you do not then the issue could be the T-con board etc. For all of those you would have to remove the back cover from your TV and take a look at the boards. You an measure the output of the power board to the LED’s with a multimeter etc. If unsure, post some good images of your boards with your QUESTION. That way we can see what you see. 在已经存在的问题里加入图片

Of course, try a reset first. Remove all video inputs as well as sounds bar etc. Then unplug the TV. Hold the power button down for something like 1 minute of keep the TV unplugged for a couple of hours. After that replace one video input (preferably local like a DVD/BR player, game console etc. Keep cable or Sat box unplugged since sometimes those can cause similar issues) After that plug the TV back in and try it out. Let us know if that made a difference.