Did you ever get sorted out with Kodi on your fire stick? Because of my injury, I watch a ridiculous amount of TV And Movies, especially in the winter. I find Terrarium has been much better as far as stability and updates over the past several months. It's very easy to install on your fire stick, and this is a video that pretty much walks you through it step-by-step. If you really want Kodi, probably the best way is to get a build where people at least update add-ons etc. I would recommend Terrarium it's been pretty solid for me.
https://www.youtube.com/watch?v=TPu5BZw3N1E&t=247s
https://www.youtube.com/watch?v=TPu5BZw3N1E&t=247s