I bought this tv I believe back in 2017 (I know the warranty expired) and I'm trying to see if anyone had an issue with the model/series as well? I tried factory resetting, and other tricks on turning it off and on with the plug itself, even leaving it unplugged for a bit. I was told it could be a video card from some threads but I'm not sure since I only was able to use it for about 3 months before it turned this way.
I'm sorry to hear that, by not properly responding does it have input lag or is the screen blurry?
Does this occur during the picture test? If it does then this will require service and since the TV is out of warranty you can use the link below to find a service center in your area to get set up for service.