The long wait is finally over. Rbox has released his TWRP custom recovery and a per-rooted ROM for the 1st generation Amazon Fire TV Stick. This will allow those of you who rooted with KingRoot or Kingo Root can now install TWRP custom recovery and use it to update to the latest 126.96.36.199 software version without losing root.
The instructions for installing TWRP are fairly simple, but I’ll have a guide up within a couple days for those who need it. Entering and controlling TWRP is different then you may be used to if you have a rooted Fire TV, since the Fire TV Stick does not have a full-sized USB port for external keyboards. You’ll need to connect the Fire TV Stick to your PC and use ADB over USB. A file needs to be created in a specific directory to enter TWRP, then once you’re in, you’ll need to use a mouse emulator program, that rbox has created, to navigate around TWRP. I’ll have more about this when I write my guide, but rbox has explained the procedure in his posts.
It is HIGHLY recommended that you perform a complete factory reset after installing the pre-rooted ROM for the first time. This is so that you remove all the junk left behind by KingRoot or Kingo Root. If you have the means, be sure to donate to rbox for sticking with this endeavour for so long and coming through in the end. He had to overcome a lot of obstacles getting TWRP to work with the Fire TV Stick, so it’s very impressive that he has pulled it off.