Interesting... The devices don't appear to be overheating, but all 3 of my new 4K's are having similar issues. I tried to submit the HDMI form on 3 different devices using 4 different browsers and when I click the continue button nothing happens.
I ordered a Fire TV Stick 4K Max (arriving Wednesday) to try. Not sure I'll like it, but it does come with faster processor, and WiFi6 which could come in useful playing my in home library of 4K rips.