I have a Vizio E55-F0/1. It would randomly just turn off. It wasn’t very often, but it happened and was annoying. I started to try different things. Someone mentioned the CEC setting and that it should be disabled. When I disabled it, it shut off more often. But I noticed that there were three options, enabled, disabled and ARC. When I looked at the back of my TV, my cable (actually Google Fiber) was plugged into the HDMI 1, which was also labeled [ARC]. So, I went back to the CEC setting and selected the ARC option. It’s been several days now and it (knock on wood) hasn’t shut off on it’s own yet. Since I’m a little OCD, I always put my cable/Google Fiber or whatever in HDMI 1. I have 4 Vizio TVs and this is the only one with CEC and the only one that shuts off by itself. I hope this is the solution and that it helps others!