As promised, rbox has released a custom recovery, based on TWRP, as well as a pre-rooted ROM of software version 5.0.4 for the Fire TV 2. Using these files, along with the recovery installer, Fire TV 2 owners running software version 5.0.4 or older will be able to root their device in a much easier and safer method than previously existed. I received early access to these files and method and can say installation is a breeze. We don’t know yet if software version 5.0.5 is rootable, so be sure you’ve blocked updates in the meantime and stay on version 5.0.4 or older. A 5.0.5 pre-rooted ROM will be released later once we acquire the download URL.
The instructions to use these files is laid out in rbox’s posts, but I’ll have my step-by-step guide out very soon if you prefer more detailed instructions. First generation Fire TV owners should not use these files on their device. Once we received the 5.0.5 software update URL, rbox will work on a new custom recovery, as well as a pre-rooted 5.0.5 ROM specifically for the 1st-gen Fire TV, so that those of you with rooted 1st-gen Fire TVs can update to 5.0.5 without losing root.