¬ just serendipity 🍀 (not just serendipity)

I decided to jailbreak my Kindle on January 1st this year, once I got aware of the WinterBreak¹ exploit, via the excellent MobileRead forums:

I am proud to present the culmination of over a year of procrastination: WinterBreak WinterBreak is a new jailbreak which works on ANY KINDLE (from the K5) on ANY FIRMWARE

Life happens though, and only now I got time to do so.

However, I took one important precaution since then, which was essential: ensure my Kindle was always in airplane mode.

Whenever the Kindle is connected to Wi-Fi, it gets OTA updates automatically from Amazon. This is generally a sensible default and the desired behavior. However, for jailbreaking purposes, you want your device to stay stuck on time and never ever ever get updates. An update could make the jailbreak cease to work. In fact, that’s exactly what happened during these last 4-5 months:

*Note that models on 5.18.x no longer work, please check the wiki’s model list for more info

I was prudent to verify it was still running 5.17.x before proceeding.

The expected time to do the whole process was about half an hour, and it’s super user-friendly. Seriously, the folks at Kindle Modding did an amazing documentation job; arguably the procedures are friendly even to non-developers. The process boils down to connecting your Kindle to a laptop (the OS doesn’t really matter), copying a bunch of files and directories over to it, ejecting it, tapping some buttons, and repeating this procedure a couple of times.

For me it took about one hour, because I was careful to take photos (in case I screwed up) and notes (for this blog post, and also for the sake of reverting the process should I want to – for example, if I ever sell the device to a third party).

Before deciding to do it, I watched this and this video which made me feel even more confident it is the outcome I was longing for. Previously.

I won’t document the jailbreak procedure here: there’s no point. First, the upstream documentation is amazing; second, the steps here would likely easily get outdated. Head over to the WinterBreak docs. Even better, read the FAQ first. That said, here are a few notes and anecdotes.

I had to disable parental controls on my Kindle. I had them enabled to prevent me from accidentally buying books from the Amazon Store². This is the closest to adblocking I could find, and I was happy with that setting. That said, one of the jailbreak steps is to open the store, therefore the parental controls must be turned off. This is not documented upstream – to be honest, most people wouldn’t be in that situation anyway.

The process failed in the first attempt. I am not quite sure why. It got stuck at the Jailbreaking — please wait... screen. The docs say:

If you do not see any funky text then make sure Airplane mode is disabled to avoid any automatic update. Turn it back on after you see the text though!

That was not helpful to me though. What worked was to restart the device and try again.

The second attempt worked.

Once the jailbreak is done, head over to Post Jailbreak. Steps:

• set up a hotfix: to ensure the jailbreak persists, even after restarting the device
• install KUAL & MRPI: package managers, basically
• disable OTA updates: important to ensure an automatic update does not revert the jailbreak
• re-enable the store: not super relevant for me, but why not – and then turn parental controls back on
• install KOReader: surely this is the most exciting part

KOReader is a document viewer for E Ink devices. Supported fileformats include EPUB, PDF, DjVu, XPS, CBT, CBZ, FB2, PDB, TXT, HTML, RTF, CHM, DOC, MOBI and ZIP files. It’s available for Kindle, Kobo, PocketBook, Android and desktop Linux.

A few highlights from the FAQ:

Is it possible to undo the jailbreak (“unjailbreak”)?

Yes, perform a factory reset on the device and then install the same firmware update (or higher).

This makes the action of doing the jailbreak a no-brainer. Sure, there’s always a (small) chance of bricking your device, but I think it’s worth the risk.

Will this get my Amazon account banned?

No reports of Amazon accounts being banned after jailbreaking have been reported so far. However, please refrain from telling support that you have modified your device.

Common sense. I never contacted Amazon Support in 11+ years of owning Kindles, so I don’t particularly care about it anyway.

Will this void the warranty on my Kindle device?

Probably.

This is always the case with jailbreaking.

It’s much easier to commit when you have an old device that is already out of the warranty period.

Avoid jailbreaking brand new devices. :)

Can I still use the default reader after jailbreaking?

Yes.

It’s true: I verified it. This is great. In the (unlikely) case I find out that KOReader sucks³, I don’t need to regret it.

Is it possible to change screensavers in the native Kindle UI?

Although there are currently no extensions to change the screensavers in hard-float firmware, it is still possible to change them, but it is not recommended as it is very easy to brick the device.

Noted. But:

You can easily change screensavers with KOReader (search for the “screensavers” feature).

How can I check if my device is jailbroken?

Type ;log into the search bar, if a message pop ups, you’re jailbroken.

And now I’m done.

I cannot stress this enough: it’s very important to read the docs thoroughly before deciding to jailbreak. RTFM!

Perhaps I’ll write a follow-up post-jailbreaking user experience blog post.

Appendix #

% tree Downloads
Downloads
├── koreader-kindlehf-v2025.04.zip
├── kual-mrinstaller-khf.tar.xz
├── renameotabin.zip
├── Update_hotfix_universal.bin
├── Update_KUALBooklet_ALLDEVICES_KS2_install.bin
└── WinterBreak.tar.gz