[Q] Still on stock rooted 4.1.2, best procedure to upgrade to stock rooted 4.4.2? topic

Sorry that I haven't been keeping up with the latest developments in bootloader unlocks, roots, recoveries, etc.

I'm on stock rooted deodexed 4.1.2 with unlocked bootloader and a probably now ancient TWRP. What is the best way for me to get to stock rooted deodexed 4.4.2? I don't see any guides for this sort of thing here. Thanks in advance.

[DEV] Bootloader unlock procedure and software topic

I get to unlock the bootloader of my kindle hdx 8.9

Prerequisite: 1[34].3.1.0 < x < 1[34].3.2.4 (as it use the rsa bug)
Rooted kindle

cat /sys/block/mmcblk0/device/manfid
cat /sys/block/mmcblk0/device/serial

create a file unlock.img with following content:
0xmmssssssss
where mm=manfid and ss=serial

encrypt it with my vortox fork of signing tool at

https://github.com/dpeddi/Cuber

./cuber_unlockbl --sign ./unlock.img ./unlock.signed

connect the hdx to a linux box and do following command:

./fastboot -i 0x1949 devices
./fastboot -i 0x1949 flash unlock unlock.signed
./fastboot -i 0x1949 reboot

adb shell
idme print
[...]
unlock_code: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAAAAAAAAAAAAAAAAMsv9S[...]WRUFx7FaA==

Regards and thank to all (Hashcode, Cpasjuste, Vortox...)

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