I've had the 4k streaming stick for a few years now. For about a year or so, I've been starting to get temperature warnings occasionally while watching content.
Well today, I decided to snoop in the secret screen, and guess what I found out?! My Roku is idling at 90C(194F), and easily reaching Temps of 110C(230F). I don't have great ventilation in the room, but this is still significantly higher than it should be.
In short, I'm looking to find if anyone has any solutions?
Have you tried the free HDMI extender? Getting it away from the TV may help.
Make sure you use the serial number displayed under Settings->System->About or listed in your account at https://my.roku.com .
There's nothing special about the Roku HDMI extension, it's just a short (4 inches or so) HDMI cord with an HDMI plug at one end and an HDMI socket at the other. I use one several feet long to locate my Streaming Stick in an equipment closet on the other side of the wall from my TV. You may be able to find an HDMI extension locally and not have to wait for someone to ship it to you.
One other possible cause of overheating is an inadequate power supply. If you recently received updates to Roku software or some key channels, they may have increased your power needs. A unit that was just getting by before may be pushed into overheating.
The USB ports on many TVs are under piwered. If the power for your Streaming Stick is from a USB port on your tv, try powering it via a USB power adapter plugged into your house power. If already doing this, try another adapter you may have around, just be sure its 5 volt dc output us at least 1 amp.