Kindle PW4 (fw 5.13.6) Jailbreaking with serial

[Naervern]

Going to attempt the serial approach for a G000 PP Kindle Paperwhite 4 that unfortunately was let to update to the fw 5.13.6 back in August. Since some other users seemed to also have troubles with jailbreaking the PW4 beyond FW 5.13.3, I hope this thread can be helpful.

This is my first time attempting both a jailbreak and to stop the autoboot using a serial interface, so thought it could be a good idea to try a new thread and gather some words of wisdom that I might have missed during the searches over the past days.

The hardware has been set up already. I'm using the FT232RL from FTDI, with a buck converter for the 1.8V as it would take a couple weeks to get an AMS 1117 1.8V VR here

Images:

Spoiler:

So far, I've only run the tests through Putty with the boot and all (ok so far), but to jump to the real thing, in booting the Diags on the Kindle, I saw that it simply deletes the boot files, but that could be solved by the battery disconnect trick, as pointed out in the thread:
https://www.mobileread.com/forums/sh...&postcount=549

As pointed out in the post #549, sadly without more details, it's said to work on PW3 with fw 5.13.7

Could this work for the PW4 as well? I've come to believe that the PW3 and PW4 have largely similar systems (same CPU and RAM allocation), though I might be wrong from some shady extra machine code put in the PW4...

[katadelos]

Originally Posted by Naervern

As pointed out in the post #549, sadly without more details, it's said to work on PW3 with fw 5.13.7

Could this work for the PW4 as well? I've come to believe that the PW3 and PW4 have largely similar systems (same CPU and RAM allocation), though I might be wrong from some shady extra machine code put in the PW4...

PW3 and PW4 are massively different all of the ways that matter:

• PW3 uses an unlocked U-Boot variant, meaning that you can actually access the U-Boot shell - not possible on PW4
• PW3 (like most older Kindles) has a separate kernel and rootfs for diags (i.e why the serial jailbreak is possible in the first place on those devices), PW4 doesn't
• PW4 uses a different CPU and said CPU has HAB/Secure Boot enabled, limiting what the device will boot in the first place
• Even if you managed to stop your PW4 from deleting the Diags update, the installer within the initramfs would still refuse to install that update (otherwise, we'd still be using that method)

That method you linked (i.e boot into diags -> load factory firmware from recovery-util -> follow factory jailbreak process) is a dumb way of doing a serial jailbreak anyway unless I'm missing something - they could've saved themselves a lot of time by just following the instructions in the first post.

[hius07]

Maybe better to continue in the existing thread
https://www.mobileread.com/forums/sh...d.php?t=313438