22 December 2025

Jailbreaking an Ancient Kindle

Model D01100

Model K4/K4S with recommended jailbreak: NiLuJe's K4 JB

Following the really simple instructions from the the jailbreak README installs a developer key into the device allowing unsigned modifications.

...it was amazingly easy!

The process for developing apps (called 'Kindlets') is described here.

Disabling OTA software updates was done by following the instructions here

To prevent firmware updates it was necessary to run the Filler.sh script from here

To undo the disk-fill, delete the fill_disk folder on the Kindle.

Trying to install MRPI/KUAL just would not work!

searching for ;log MRPI just did nothing

dropping the KUAL directly into the documents didn't work because it complained the app was not signed.

Then I stumbled across MakerBlock's blog post about being able to SSH into the Kindle.

I downloaded the dev certs from here and installed them.

Then I got KUAL to run!

...and to display 'Mobileread Kindlet Kit is not installed' :/

So presumably I've screwed something up somewhere, but I can't see how to get ;log mrpi to run. Figuring that out will have to wait for another day.

Update (28th December 2025): Success!

I had ignored the 2014 dev certs package because I had assumed the 2025 version was all I needed.

Having successfully got KUAL running on the K3 made me think it might require both.

So I:

Copied Update_mkk-20141129-k4-ALL_install.bin and updated

...this led to me not being able to run the KUAL document because it wasn't signed, so then I:

Copied Update_mkk-20250419-k4-ALL_keystore-install.bin again and updated

...and it worked! :D

So the 2014 update contained more than just the certificates and needed to be installed BEFORE the 2025 one.