The eMMC does not have as "smart" a micro-controller built-in as an SSD does, but it does have one and we will try various ways to get it to map-out the bad erase blocks.
The sequence is:
U-Boot menu -
Recovery menu -
We will start at the higher level ( the recovery menu ):
#1 - Stop the boot sequence at the "recovery menu" place
The recovery menu will have an "export usb storage" (or words to that effect) selection.
Hook up USB cable to PC, select that choice.
Note: You may have to type something every 5 .. 10 seconds to keep the menu from timing out - space usually works.
When that selection is made, your PC's automation should auto-mount it and open a file manager (just as if it where normal).
Delete the update file(s) - you probably have both a *.bin and a *.stgz (or something like that).
Add the: "DO_FACTORY_RESTORE" flag filename to visible root.
With file manager: "eject"
Remove USB cord
With the Recovery Menu - "Exit" or "Reboot" or whatever it is named.
It it doesn't restart, restart it with the power button, wait.
You can watch what is happening on the serial port - it **might** loop, trying to write an erase block, error, map-out, try again - - - etc.
And eventually run (even with the mis-matched kernel / kernel-modules.
The worse that can happen is it will get hung again in another hardware failure loop.
#2 Presuming the above failed to do any good -
From the JB thread:
https://www.mobileread.com/forums/sho...d.php?t=275877
Step #3, get the factory initial firmware for a PW-2 (and its MD5SUM).
As above, enter Recovery Menu, Cable, Export USB storage, put that factory initial firmware at the root of visible storage.
CHECK ITS MD5SUM - remember we are working with flaky storage.
Repeat moving the factory initial update file to the Kindle until you get a good copy in-place (the micro-controller is a bit dumb, it will only map out one block per try).
Got that in place?
eject, remove cable, reboot (menu or power button).
Your trying something un-tried so far - see if the factory initial firmware can recover the device - - I **think** this is the package that the "refurbish" people use.
If your lucky, that will fix it.
If not - we will have to get serious and tackle it at a lower level.