[knc1]

Exactly.

Let's assume a Linux PC and a 'normal' Kindle -
(You will have to adapt for your own situation.)

Connect Kindle to PC with USB cord.

Depending on your Linux distribution's flavor of automation -
It should 'auto-mount' and is likely to pop up a file manager.

In a PC terminal, do:
dmesg

The last few lines will tell you what device the system assigned.
For instance:
/dev/sde (raw storage) and /dev/sde1 (first partition).

**EJECT** the Kindle's storage appearance (file manager or command line).

The first portion of /dev/sde contains the DOS label with mbr and partition table - corrupt those, as in:
dd if=/dev/zero of=/dev/sde bs=4096 count=16
Note that we are writing to the raw storage device, not the partition.

Remove USB cord between Kindle and PC -
Put USB cord back between Kindle and wall charger (because USB ports have been known to power off after a delay) -
re-boot (press and hold power button 30 seconds or more) -
wait.
the start-up routine will discover that USB storage is not formatted and will re-format it.
if the format routine runs into errors - it will restart.
if you have 2K bad erase blocks, expect about 2K restarts.

rinse, spin, repeat until it can re-format the USB partition without generating any restarts.

= = = =

If you work cheap, say $50/hour or less, then you can do the above more than once.
Otherwise, it isn't worth it, sell it for parts.