Changes and TV makers rarely keep up. The cheapest fix I know of depending on if you have an Amazon Prime account would be the Amazon Fire Stick. After that would be a Roku stick.
You've completed the basics so what's left is to ask the maker if they have a fix. I can write that out of say 100 times folk have asked the maker has not fixed this 99 times or closer to 100.
You tube used to work on my TV but now when we press YouTube it just comes up saying YouTube and goes no further than that. We have tried unplugging everything and trying again but no and tried first time installation again but with no luck for you tube. Any help be much appreciated