i've seen a lot of junk responses on here. idk if you have found a solution or just got a new TV (worst advice ever, like saying, "oh, computer trouble? just reinstall windows.") so if so, then this reply may still help someone.
after having the same issue for weeks, i had been dealing with it, but tonight it was bad. since i use my RokuTV as a secondary monitor, it is set to be on HDMI1, and that's all i use it for now, but it kept loading other channels, muting, and powering down. after i did hit the reset button, it was still happening. so i chose HDMI1 again, and then hid the remote under a shirt. still happening. then porn showed up. and it was the same video 3 times. so i thought it may be someone here in this hotel, so i put the shirt over the remote sensor. problem solved. another thing to consider is that you may be having the random things happen because the other person is testing buttons and powering it down because theirs is not acting right because of your buttons being pressed, and being on the same wifi network may not be helping.