Manual firmware downgrade from shell

[aholmes5]

For kindles that can't be downgraded via a Factory image, would the following commands work or would this destroy the kindle? This is what I did to restore an PW2 to 5.4.0.

1) Extract the older firmware image with KindleTool to /mnt/us.
2) Boot to rescue partition using rescue pack or serial port and exit to command prompt.
3) Run: zcat /mnt/us/mmcblk0p1.bin.gz| dd of=/dev/mmcblk0p1 bs=4096
4) Run: dd if=/mnt/us/main_kernel.img of=/dev/mmcblk0 bs=4096 seek=65
5) Might need an "echo 0 > /var/local/upstart/lab126_gui.restarts
6) Reboot: idme -d --bootmode main && reboot
7) Hopefully reboots into older firmware then do a reset device from main menu.
8) Rejailbreak with factory JB or serial.

[Junket]

Kudos on restoring your PW2.

I have no experience with PW2. The approach looks good, but whether this would work in whole or part on another Kindle model is depends on many variables. For instance the PW4 file system is androidized and isn't a dual boot system where you could use rescue this way, file signatures are enforced more rigorously, et cetera.

But you might take that as a challenge rather than an obstacle.

[MrTick]

Originally Posted by aholmes5

(...)
2) Boot to rescue partition using rescue pack or serial port and exit to command prompt.
(...)

This step is currently impossible (at least for PW4) since 5.10.3.
Serial terminal is locked and offers very few commands.

[knc1]

Steps 3, 4 and 5 are wrong and none of the rest are needed.
And yes, if you do any of 3, 4, or 5 the Kindle will be "destroyed".

Just follow our published directions on using the serial port, don't try to make them up as you go along.

[NiLuJe]

FWIW: I seem to recall a bunch of scripts by @geekmaster and @knc1 to pinpoint the kernel offsets automagically, because these might be a moving target, so using fixed offsets might be A Terrible Idea .

(That's basically just another vote for: think before you blindly type commands you found on the 'net as #).

[knc1]

Originally Posted by NiLuJe

FWIW: I seem to recall a bunch of scripts by @geekmaster and @knc1 to pinpoint the kernel offsets automagically, because these might be a moving target, so using fixed offsets might be A Terrible Idea .

(That's basically just another vote for: think before you blindly type commands you found on the 'net as #).

Geekmaster created basic backups using a fixed location.
knc1 extended those scripts into a system backup add-on for KUAL.
That backup thing is a rather simple script, just read it for details.
(advanced search, my nic' as author, "backup" in the title)


BIG NOTE: I never updated those backup scripts for the "Androidized" Kindle firmwares.


Of Lesser note:
My text entry thingy claims "Androidized" is not a word.
We have used it often enough now to have it included as part of current English.

[hius07]

Here it is, Kindle backup
https://www.mobileread.com/forums/sh...d.php?t=289690