Lowered my Roku Stick's temperature by 10 degrees (from 101° C to 91° C). Did 2 things.
First- installed an extended cable having my Roku Stick away from the tv.
Second- (and this is sort of a caveman repair but I dont care - lol) attached an old pc video card heatsink to it with electrical tape-lol. I was not willing to open the enclosure and since the plastic was overheating as well I decided to "attach" the heatsink to the plastic case of the Roku Stick (with thermal paste and all) using electrical tape. Does not looks good but its behind the tv so ...
Temperature went down and the annoying message stopped. So its all good. And the electrical tape is holding... hahaha.