[Fire HD 6 and 7 General] Have Blue:
Hi, I just created an account to say thanks! I'm a complete newbie to Android but needed to get a cheap Android device to do some testing for work. I figured a refurb Kindle HD 6 would fit the bill, only to find that it's pretty locked down and didn't allow me to run the apps I needed. Well, after a day or two of messing around with drivers, installing Android Studio, learning the difference between adb and .apk (like I said, I was beginning as a total n00b to Android, though I've been a Linux user for years), I have a usable device!

Here's a brief summarized rundown of what I encountered:

I forget precisely what version the device shipped to me with, but I believe it was mentioned to be a non-rootable build, so I did the OTA update to 5.1.2.

The OTA update gave me the March build of 5.1.2, so I used the instructions to 'adb sideload' the February 5.1.2 version.

I used 'adb install' to push KingRoot to the device, then had to try running it a few times before it was finally successful.

I started panicking a bit at this point, since the device showed under 'System Updates' that 5.3.1.0 had been downloaded and would be installed when I wasn't looking (well, I don't know if that's how it works, but I got pretty worried)

I managed to get a file manager (ES File Explorer, I think it was) installed and tagged with root privileges so that I could add an underscore to DeviceSoftwareOTA.apk as suggested before the device tried upgrading by itself. Phew!

I grabbed WindowsAutoTWRP_v03.zip and ran everything successfully - what a nice little tool that is! I downloaded all the recommended .zip files and installed them with TWRP one-at-a-time. Well, except for the Pico/Uni GAPPS - my computer was no longer showing the connected filesystem on the device at that point, but that was the last package to install, so I figured I'd just reboot it and install it once more with TWRP. After all, I had a rooted device now, right? Right?

After rebooting, KingRoot seemed to indicate that the device was no longer rooted. Ahhh, crap, I messed up somehow... And now it shows 5.3.1.0 as the installed version! But that can't be rooted! What do I do?!?

Throw caution to the wind, and sideload the February 5.1.2 build again. I mean, bibikalka says to thank him for being able to recover so easily...

Hey, that worked - I'm back at 5.1.2. However, the device is acting wonky - after all the icons load, it then shows a black 'desktop' briefly, then loads the icons again, they disappear to black again, repeat...

Somehow I managed to run KingRoot a few more times and eventually get back to TWRP again. Phew!

This time I did all the TWRP steps, even the optional ones (except for backing up - I had no data to back up).

I noticed that TWRP allowed for selection of multiple installs (up to 10) to be queued up, rather than doing them individually. I wondered if bibikalka's admonishment of "in a single session (!!!!!)" referred to this - I had assumed a 'single session' meant "don't reboot between installing these .zip files"

This time I queued up all 6 .zip files and installed them in a group.

Rebooted to recovery, saw that it was the stock recovery, not TWRP, just as it should be.

Rebooted to the OS, waited for it to initialize, and hooray, success! KingRoot was no longer there, so I knew it had taken hold properly this time.

Not sure specifically what I did wrong the first time, but I managed to recover and get things working in the end without bricking the device. So thanks again bibikalka!