The Linux bootlog is correct. You can find the fastboot thread here
https://www.mobileread.com/forums/sh...d.php?t=171460
I use this on a very old laptop with Windows XP. I do not know if it will work on 64bit versions of Windows. In case of something here
https://github.com/TobiasWooldridge/Fastboot-Kindle There is a Fastboot that should work on Linux.
Good luck.