We have many posts on this. I also post in my mega guide that amazon updates can only be blocked on older versions.
Please review this for all firestick issues and guides, if the following hasn’t worked feel free to ask.
This should resolve most to all issues.
Also it seems amazon may have just blocked the newset way for updates. Also, there is no fuss with amazon unless you want to fully customize it if you want to do that than you shouldnt use a stick.