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Kindle K4 Jailbreak

Registering your kindle #

it looks like you need a registered kindle to apply the jailbreak,
as of now (2026-08) it shouldn't be possible to register devices released prior to 2012,
our Kindle 4 is in this list:
https://www.amazon.com/gp/help/customer/display.html?nodeId=TRXsYxKJr4WTdsVs2P

But it seems there is a workaround to register it, which worked on my Kindle 4:

1 - Reboot Kindle.
2 - Log in with Amazon account + password to trigger the OTP email
3 - Check email for OTP code.
4 - Restart the Kindle again (making sure you do so within the 10 minute window before OTP expires)
5 - Login again but use the OTP code instead of your password (do NOT use the password+OTP code method).

source: https://www.reddit.com/r/kindle/comments/1ma7cqs/comment/nxujaua

Jailbreaking #

The guide for the Kindle 4 on kindlemodding.org does not seem to work,
I've followed these instructions and they worked correctly for me.

The bulk of the steps are from this reddit post:
https://www.reddit.com/r/kindle/comments/1ipko3u/comment/mcw6m8t

I've added step 8 because I got the message
"an error occurred: main class instanstantion threw a Runtimeexception"
while launching Kual.
It seems that the jailbreak wrongly installs a booklet which is not compatilbe with our device.

1 - Update firmware
If your Kindle's firmware is already version 4.1.4, you don't need to do anything.
If it's lower than 4.1.4, follow the instructions here (https://www.amazon.com/gp/help/customer/display.html?nodeId=GFAE5G5UGCYA25DW) to update.
Note: You will need to either register your Kindle to an Amazon account, or always keep it in airplane mode. If your Kindle is unregistered and connected to Wi-Fi, it will cause some of the following steps to not work correctly and you will not be able to open KOReader.

2 - Install Jailbreak
Download "Kindle 4 Jailbreak" archive from here (https://www.mobileread.com/forums/showthread.php?t=225030), and follow the instructions in the README file to install it.

3 - Install MKK
Download "Mobileread Kindlet Kit" archive from the previous link.
Find the file labeled "Update_mkk-20141129-k4-ALL_install.bin" in the archive and copy it to your Kindle's root directory.
Use the "update your kindle" option in the Kindle settings menu.

4 - Install KUAL
Download "KUAL" archive from the previous link.
Find the "KUAL-KDK-1.0.azw2" file in the archive and copy it to your Kindle's documents folder.

5 - Install DevCerts update
Download the DevCerts zip file from here (https://www.mobileread.com/forums/showpost.php?p=4506164&postcount=1295).
Find the file labeled "Update_mkk-20250419-k4-ALL_keystore-install.bin" and copy it to your Kindle's root directory.
Use the "update your kindle" option in the settings menu.

6 - Install KOReader
Download "koreader-kindle-v*.zip" archive from here (https://github.com/koreader/koreader/releases/latest), and install it just by unzipping it to your Kindle's root directory.

7 - Use the KUAL entry in your Kindle's library to launch KOReader.
Which will fail because we still haven't executed the next step

8 - Fix KUAL
From the archive of KUAL in step 4, retrieve the file Update_KUALBooklet_v2.7.37_uninstall.bin,
place it in the root of your kindle and use the "update your kindle" option in the Kindle settings menu.

9 - Now Execute KUAL!