Originally Posted by Maslan
btw I still don't know what will do bootloader-3.3 and the rest from 3.4 after another upgrade of FW if there was any.
Not a problem. The 'bootloader' rarely changes (until 5.3.0).
The chance of there being a 3.4++ firmware is between slim and none.
(Any e-ink display Kindle with audio competes with the Kindle Fire and Kindle Fire HD.)