Fire HD 8 (2018 ONLY) unbrick, downgrade, unlock & root

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zomgitsanoob

Senior Member
Feb 3, 2013
150
29
Nothing happened when I shorted CLK and plugged in the cable. I then had to wait several minutes and hold the power button down for a long time to get the device to start normally. What am i doing wrong?

-device off

- ran ./bootrom-step.sh

-shorted clk to the shield/spreader

-plugged in cable
 
Last edited:

Falcon342

Senior Member
Aug 24, 2020
194
69
Nothing happened when I shorted CLK and plugged in the cable. I then had to wait several minutes and hold the power button down for a long time to get the device to start normally. What am i doing wrong?

-device off

- ran ./bootrom-step.sh

-shorted clk to the shield/spreader

-plugged in cable
You need to plug the cable in first then short the CLK
If you need a guide here is a good one:
 

Kovaelin

Senior Member
Aug 19, 2015
57
18
Canada
Now when I run the brick.sh I'm getting this error:



any ideas?

Thanks.
I'm also getting this error at the bricking step.

FAILED (data write failure (Protocol error))

I'm on 6.3.0.0 and not sure how to proceed. Any help would be appreciated!

UPDATE: After a bit of digging, I found the right path here: [UNLOCK][ROOT][TWRP][UNBRICK] Fire HD 8 2018 (karnak) amonet-3 | XDA Developers Forums (xda-developers.com)
Extract the attached zip-file "amonet-karnak-v3.0.1.zip" and open a terminal in that directory.

I should have read the outputs more carefully, because it does refer you here when it fails: Rapid Temporary Root for HD 8 & HD 10 | XDA Developers Forums (xda-developers.com)
I thought there may have been another way to get root, but it seems that is the way to do it.

Thank you to Michajin.
 
Last edited:

Else01181

New member
Mar 7, 2021
3
0
No - it runs the script and I get to "Reboot to unlocked fastboot".

Also, i was mistaken. After running the steps again, at this point the device powers up with the white "Amazon" logo. I do not understand what I need to do next.

Do i need "Reboot to unlocked fastboot" mode myself? if so, how?
New here... Trying to unlock Fire HD8 2018 using fireOS 7.3...
Basically script bootrom-step.sh was working till the end without any failure and ended with "Reboot to unlocked fastboot". So far so good.
Thing is neither the Amazon logo appeared nor anything else is no working - the Fire seems not to boot any more.
I have disconnected the battery for minutes. I was waiting between the steps for minutes and also was pressing power button for almost a minute but nothing.
Also recovery mode is not starting (using Vol- button and power button at the same time).
So in case some else was being to Fire back to work, I would love to know how ... THANKS!
 

Michajin

Senior Member
Oct 23, 2012
1,245
486
New here... Trying to unlock Fire HD8 2018 using fireOS 7.3...
Basically script bootrom-step.sh was working till the end without any failure and ended with "Reboot to unlocked fastboot". So far so good.
Thing is neither the Amazon logo appeared nor anything else is no working - the Fire seems not to boot any more.
I have disconnected the battery for minutes. I was waiting between the steps for minutes and also was pressing power button for almost a minute but nothing.
Also recovery mode is not starting (using Vol- button and power button at the same time).
So in case some else was being to Fire back to work, I would love to know how ... THANKS!
What device shows up under lsusb? if you see MediaTek PHone 6227 you are stuck in the bootrom. Chances are you are stuck in bootrom or preloader. Once your screen displays hacked fastboot, you can run the fastboot step. If you made it through this, you should be safe to run the brick script, which can fix some issues. Try running the bootrom-step again and see if it detected or has any GPT errors or anything else flagged.
 

Else01181

New member
Mar 7, 2021
3
0
What device shows up under lsusb? if you see MediaTek PHone 6227 you are stuck in the bootrom. Chances are you are stuck in bootrom or preloader. Once your screen displays hacked fastboot, you can run the fastboot step. If you made it through this, you should be safe to run the brick script, which can fix some issues. Try running the bootrom-step again and see if it detected or has any GPT errors or anything else flagged.
I set up a persistant Linux system on an old machine (something I was planning for decades :LOL:) ... and tried to run bootrom-step again with HW method, and this time it started but as you already assumed, GPT failure occured. So I am now checking the forum how to fix but so far nothing found yet
 

Michajin

Senior Member
Oct 23, 2012
1,245
486
I set up a persistant Linux system on an old machine (something I was planning for decades :LOL:) ... and tried to run bootrom-step again with HW method, and this time it started but as you already assumed, GPT failure occured. So I am now checking the forum how to fix but so far nothing found yet
Is there a gpt-fix.sh included in the amonet?
 
Using a fresh copy of Ubuntu, will, try your suggestion when I get access to the tablet.
To confirm, is it safe to use this method to root when my fire os is 6.3.10?
or, use the WSL2 Kernel to install Ubuntu to Windows. I have only been able to get Kali Linux booted with a GUI with that method, but Ubuntu, Debian, openSUS, and others are all available from the Microsoft Store. I suggest also downloading either Windows Terminal or Terminal Preview for added functionality, as well as Powershell 7.1.3.
 

PAsongers

New member
May 5, 2021
4
0
Hi All,

I started this process by following the Destination Linux Network YouTube video, which has been very helpful. I am very sorry if this is a stupid question, but I am stuck on step 10 (so close). I've been stuck here for a few days. I can't figure out the solution :(. Whenever I run fastboot-step.sh, I receive the following:

fastboot: error: cannot load 'bin/recovery-inj.img' : No such file or directory

I see my device listed when I run 'fastboot devices' and I had no issues with the previous steps. I also tried running bootrom-step.sh again to start over. I have no issue there. But when I try running fastboot-step.sh, the error is always the same. I am currently running Manjaro and below is a screenshot of the error.

Error snapshot.png


Any advice?

Thank you!
 
Last edited:

sky1984

New member
May 6, 2021
1
0
Hello,

I can't get my Fire HD 8 (8th Generation) to boot into TWRP, nor boot OS at all.
Running boot-recovery.sh script ends ok and device boots into fastboot mode. I can see it with 'fastboot devices' command, but then running fastboot-step.sh exits with an error:

fastboot: usage: unknown reboot target recovery

So i rebooted normally with 'fastboot reboot' command but then there is this white Amazon logo and then it reboots itself after some time, not showing TWRP nor OS. On Wendy's video she presses the power button twice. Also tried that without any luck.

Downloaded amonet-karnak-v3.0.1.zip and same issue. I can boot into hacked fastboot but not into TWRP recovery so its stuck on Amazon logo.

What else should I try to fix it?

-- Nevermind, I kept trying the same ./fastboot-step.sh and suddenly it worked (after maybe 20 reboots).
 
Last edited:

Falcon342

Senior Member
Aug 24, 2020
194
69
Hi All,

I started this process by following the Destination Linux Network YouTube video, which has been very helpful. I am very sorry if this is a stupid question, but I am stuck on step 10 (so close). I've been stuck here for at least 5 hours between yesterday and today. I can't figure out the solution :(. Whenever I run fastboot-step.sh, I receive the following:

fastboot: error: cannot load 'bin/recovery-inj.img' : No such file or directory

I see my device listed when I run 'fastboot devices' and I had no issues with the previous steps. Any advice?
As the fastboot error states it seems like there is missing or corrupt files
 

PAsongers

New member
May 5, 2021
4
0
I thought I was done, but I am having an issue when installing 6300.zip. I keep receiving the message "updater process ended with ERROR: 7." Below is a screenshot. Any advice on what I need to do?

Thank you!

20210506_162835.jpg
 

kellyvotrenom

Member
Aug 9, 2019
32
5
Trying this for the second time on another tablet and not having much luck. When trying to run sudo ./bootrom-step.sh I do not get this response

[10894.058045] usb 3-2.4.1: new full-speed USB device number 9 using xhci_hcd
[10894.239684] usb 3-2.4.1: New USB device found, idVendor=0e8d, idProduct=0003
[10894.239690] usb 3-2.4.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[10894.241330] cdc_acm 3-2.4.1:1.0: ttyACM0: USB ACM device

What I see is

[2021-05-22 19:37:41.933530] Waiting for bootrom
[2021-05-22 19:37:49.526461] Found port = /dev/ttyACM0
[2021-05-22 19:37:49.530414] Handshake

and then it hangs

Checking lsusb it shows
Bus 006 Device 039: ID 0e8d:2000 MediaTek Inc. MT65xx Preloader
with or without the short

Been digging thru the thread and not understanding what my options are at this point. Tried a bunch of different cables and ports.
Running Ubuntu 18.04 - last time I think I was still on 16.04. Modem Manager has been removed from the system.

What should my next step be?

Thanks
 

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  • 1
    Try different cables and ports, I've had it make a difference. Even though the general advice is that if you are stuck at "waiting for bootloader" you don't have a good short from clk to ground, I have my suspicions that it may also be a communicatons error. I am certain that I had a good connection this last time I tried and it kept hanging. I think changing ports on the computer helped the problem. I also believe I have seen in the posts to use a USB 2.0 over 3.0 port, but try them all. This has applied in other situations for me, like external drives and tablets that don't get recognized until you find the right combination of port and cable.

    Also, did you remove Modem Manager?
    1
    And if you have keeping the battery connected, one advice is temporally disconnect the battery plug. The power will be provided through the usb cable.
    1
    Having USB debugging on should not mess it up, infact i think you are supposed to have USB debugging enabled,
    i recommened trying what @kellyvotrenom & @Korin67 said and see if that helps.
    Thanks guys! I'll post if I get it. or to shamelessly beg for help again, depends.
  • 108
    VWWdRf9.jpg

    Changelog:
    v2 - Fixed the issue with the screen


    Make sure to read this guide completely before starting. It requires you to open the tablet, however you don't need to solder or use any advanced tools.

    This is only for Fire HD 8, 8th generation, also known as karnak or KFKAWI. It's now confirmed to work on both 16GB and 32GB models.

    You will lose all data on the tablet, make a backup of important data before you start. If you've enabled encryption, it's probably a good idea to disable it before you proceed with the guide.

    What you need:
    - a Linux installation. Since I had to rush it, this guide is only for Linux. Once I get a chance to test it on Windows I'll update the guide.
    - microusb cable to connect your tablet to the PC
    - some way to open the tablet (pry tool, opening picks, etc)
    - something conductive (metal tweezers, a paper clip, a piece of wire, etc)
    - amonet.tar.gz
    - 6300.zip: https://mega.nz/#!FI1HSI5T!2zUAeiW9I-eH3Ph0Ar10_2nioNIm0ilSnNYgOG9YPNE
    - Magisk-v18.0.zip: https://github.com/topjohnwu/Magisk/releases/download/v18.0/Magisk-v18.0.zip
    - finalize.zip

    Install python3, PySerial, adb and fastboot. For Debian/Ubuntu something like this should work "sudo apt install python3 python3-serial android-tools-adb android-tools-fastboot".

    Extract amonet.tar.gz, open a terminal and navigate to it.

    You might need to run the scripts on your PC under sudo if you're getting permission errors.

    0. Shut your device down and disconnect it from USB! Also, disconnect all other Android devices you might have connected from your PC. Also, if you have ModemManager installed, you MUST disable or uninstall it before you begin
    1. Use a pry tool to remove the back shell from the tablet. Start at the bottom and work your way up. There are no cables between the back shell and the motherboard.
    2. On the left side of the board there are 4 test points labeled DAT0, RST, CMD, CLK. We only care about the bottom one, CLK.
    3. Plug in one end of the microusb cable, either to the PC or to the tablet, whatever's more convenient.
    4. On your PC, run `./bootrom-step.sh`. It should print "Waiting for the bootrom".
    5. Using your conductive apparatus, short the CLK test point to the ground. This means you should connect one side of your paperclip to the CLK pin and the other to the metallic shield or a side of the PCB. Firmly hold it in place so that there is connection. (See https://i.imgur.com/7BXIb2y.jpg)
    6. Plug in the other end of the microusb cable.
    7. You should see a new device appear on your PC

    Code:
    [10894.058045] usb 3-2.4.1: new full-speed USB device number 9 using xhci_hcd
    [10894.239684] usb 3-2.4.1: New USB device found, idVendor=0e8d, idProduct=0003
    [10894.239690] usb 3-2.4.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
    [10894.241330] cdc_acm 3-2.4.1:1.0: ttyACM0: USB ACM device

    This *must* be the device you see. If you see a "preloader" device instead, you didn't hold the paperclip strong enough. Unplug it, shut down your Fire (pull out USB cord and wait; if it doesn't shut down, you might have to disconnect the battery) and try again starting at step 4.

    8. The script you ran in step 4 should now tell you to remove the short. Remove the paperclip and press Enter as instructed.
    9. The script will now proceed to downgrade your device and flash some essential files. Just let it be, it will take about 4 minutes. You should see the following output:

    Code:
    [2019-01-26 23:30:02.157670] Waiting for bootrom
    [2019-01-26 23:30:20.438333] Found port = /dev/ttyACM0
    [2019-01-26 23:30:20.439362] Handshake
    [2019-01-26 23:30:20.441693] Disable watchdog
    
     * * * Remove the short and press Enter * * * 
    
    
    [2019-01-26 23:30:22.636037] Init crypto engine
    [2019-01-26 23:30:22.661832] Disable caches
    [2019-01-26 23:30:22.662505] Disable bootrom range checks
    [2019-01-26 23:30:22.685773] Load payload from ../brom-payload/build/payload.bin = 0x4690 bytes
    [2019-01-26 23:30:22.693170] Send payload
    [2019-01-26 23:30:23.527965] Let's rock
    [2019-01-26 23:30:23.528832] Wait for the payload to come online...
    [2019-01-26 23:30:24.260602] all good
    [2019-01-26 23:30:24.261069] Check GPT
    [2019-01-26 23:30:24.596346] gpt_parsed = {'proinfo': (1024, 6144), 'PMT': (7168, 9216), 'kb': (16384, 2048), 'dkb': (18432, 2048), 'lk': (20480, 2048), 'tee1': (22528, 10240), 'tee2': (32768, 10240), 'metadata': (43008, 80896), 'MISC': (123904, 1024), 'reserved': (124928, 16384), 'boot': (141312, 32768), 'recovery': (174080, 40960), 'system': (215040, 6354944), 'vendor': (6569984, 460800), 'cache': (7030784, 1024000), 'userdata': (8054784, 22722527)}
    [2019-01-26 23:30:24.596619] Check boot0
    [2019-01-26 23:30:24.841858] Check rpmb
    [2019-01-26 23:30:25.051079] Downgrade rpmb
    [2019-01-26 23:30:25.052924] Recheck rpmb
    [2019-01-26 23:30:25.949978] rpmb downgrade ok
    [2019-01-26 23:30:25.950284] Flash lk-payload
    [5 / 5]
    [2019-01-26 23:30:26.471797] Flash preloader
    [288 / 288]
    [2019-01-26 23:30:44.845804] Flash tz
    [6732 / 6732]
    [2019-01-26 23:33:08.502134] Flash lk
    [685 / 685]
    [2019-01-26 23:33:23.337460] Inject microloader
    [4 / 4]
    [2019-01-26 23:33:23.667547] Reboot to unlocked fastboot

    If the script freezes at some point, you will have to restart it. Terminate the script, unplug USB, and try again starting at step 4. If after unplugging USB cable the device doesn't shut down, you might have to disconnect the battery. You can keep it disconnected until the script succeeds, but once it's done you must reconnect it before booting to fastboot.

    9. You should see a success message: "Reboot to unlocked fastboot". Only proceed if you see the message.
    10. Once the device boots to fastboot (check with "fastboot devices". You should see amazon logo on the screen.), you can run "./fastboot-step.sh". Then, flip the device over so that you can see the display.
    11. At this point the device should boot into recovery, however it's possible that the screen will be off by default. Just press the power button twice and the screen should turn on.
    12. We'll now upload required files to the recovery. On your PC, do:

    adb push 6300.zip /sdcard
    adb push Magisk-v18.0.zip /sdcard
    adb push finalize.zip /sdcard

    13. In the recovery, go to "Install", navigate to "/sdcard" and flash 6300.zip
    14. Go to "Wipe" and do the default wipe, then reboot
    15. At the Fire setup screen, select your language. On the next screen, Wifi setup, select any password-protected network, then instead of entering the password press "cancel". Now, back at the wifi setup screen, press "skip" and "skip" in the dialog pop-up again
    16. Hold down the power button, press Restart and hold volume down to boot into recovery.

    17. In the recovery, go to "Install", navigate to "/sdcard" and flash Magisk-v18.0.zip
    18. Press back, select finalize.zip and flash it
    19. Once finalize.zip is flashed, press "Reboot System"

    20. Done. The device should now boot into a rooted 6.3.0.0 firmware. You should have Magisk manager installed, and root working. You will be able to boot into recovery by holding volume down.
    21. At this point it should be safe to connect to wifi. If everything works okay, assemble your device.

    Your device is now unlocked. You can flash a custom boot image, system image, etc. However, if you ever brick the device so bad the recovery does not boot, you will have to repeat these steps starting from the first one. Read below for what you should not do.

    VERY IMPORTANT STUFF:
    Only ever flash boot images from TWRP. Since nothing but TWRP is aware of the exploit, if you try to flash a boot image from Android, it won't have the exploit integrated into it! This includes Magisk as well, so do NOT install or uninstall it from Magisk Manager (However, installing modules should be fine; although it depends on the specific module).

    Due to how the exploit works, it takes over the first 0x400 bytes of boot.img/recovery.img. When flashing zips from the recovery, it will transparently remove and then reinstall the exploit when needed. So long as you flash zips from the recovery, you should treat the boot image normally. However, this means that you cannot use any other apps (e.g. FlashFire) to flash the boot or recovery partitions.


    To revert back to stock:
    - download update package from amazon https://fireos-tablet-src.s3.amazon...ate-kindle-NS6301_user_1611_0001309035396.bin to your PC
    - flash 6300.zip from twrp
    - flash revert-stock.zip from twrp
    - wipe data
    - reboot to recovery; you should see amazon recovery now
    - select "apply update from ADB" in the recovery menu
    - run "adb sideload update-kindle-NS6301_user_1611_0001309035396.bin" on your PC


    Another way to fix a brick:

    - Download update package from amazon https://fireos-tablet-src.s3.amazon...ate-kindle-NS6301_user_1611_0001309035396.bin to your PC
    - Download and unzip revert-stock.zip
    - Do steps 0 to 9 from this guide (so everything until fastboot-step.sh)
    - Wait for device to boot into fastboot mode (check with "fastboot devices")
    - Run "fastboot flash boot boot.img" using boot.img from the revert-stock.zip
    - Run "fastboot flash recovery recovery.img" using recovery.img from the from the revert-stock.zip
    - Run "fastboot reboot recovery"
    - Select "apply update from ADB" in the recovery menu
    - Run "adb sideload update-kindle-NS6301_user_1611_0001309035396.bin" on your PC


    Other misc information / troubleshooting:
    - If you need to disconnect the battery, use a pair of tweezers to grab the wires and gently pull towards yourself. You can do bootrom-step.sh either with or without the battery connected, however fastboot-step.sh should be done with the battery connected.
    - If your device is bricked (e.g. from a downgrade), just follow the steps as-is.
    - If you're getting an error like "Serial protocol mismatch", or any other error in bootrom-step, try disabling or temporarily uninstalling ModemManager from your Linux
    - To remount /system as rw use "mount -o rw,remount /system". ("mount -o remount,rw /system" will not work)

    Thanks to: @hwmod @firetablethelp for testing different versions of the payload.
    Special thanks to: aftv2-tools contributors https://gitlab.com/zeroepoch/aftv2-tools; the bootrom download protocol scripts are largely based on their work
    21
    GPL Notice:
    - Source code for modified TWRP is available from https://github.com/xyzz/android_bootable_recovery
    - Source code for amonet/brom-payload is available from https://github.com/xyzz/amonet/tree/master/brom-payload

    Device tree to build TWRP: https://github.com/xyzz/android_device_amazon_karnak

    Additionally, source code of the full exploit chain is available from https://github.com/xyzz/amonet

    When I finish the writeup for this vulnerability, I'll update this post with a URL to the writeup.
    7
    Unless you hide root CTS will always fail. Not easy to do even with magisk.

    The 'Magisk Hide' option (enabled by default) is sufficient on my phone to pass CTS, and I'm not doing anything other than that to hide Magisk. I'm just using the defaults, as I am on the Fire, yet one passes and one doesn't. Only if I disable that option then CTS fails (and basicIntegrity).

    6.3.0.1 was bugged for me on first launch. I had to disable the Device Setup app via adb and then it was ok. On the plus side, it fixes the SD card setup bug (it stops asking what to do with it every boot) and the bug with some accessibility options being empty (can't toggle on/off).

    Here is a link to 6.3.0.1 for those not sure about zipping/editing the script. If anyone tries flashing it, and it doesn't work, be specific. Like does Magisk throw an error (if so, what does it say), or is there an issue post boot or.. etc?
    7
    OK, this is the paper that I had in mind. It's by XDA member @djrbliss from 2013 for the Galaxy S4. And this is the thread he made.
    Damn, if you were not aware of that work and came up with your exploit independently, that's even more amazing. My hat's off to you sir. ;)

    Interesting, definitely wasn't aware of this (and I guess neither was mediatek). So I guess what happened is both mediatek and qualcomm took Google's aboot which had no checks for boot.img load base, and added their own signature checking on top. Kinda amazing that it's been known for over 5 years.

    I also had to exploit it in a different way, I see in that blog he's overwriting a function with his code, but in my case I have to overwrite a function pointer and set up a rop chain to do cache flush before jumping to the payload. Either way, the end result is the same.
    7
    This is very promising could you please elaborate, what exactly needs to be modified to port this to other MTK-hardware.
    I have a fire 5th gen here and I can access brom-mode by pressing left mute button while pluging in.
    tried your scripts as is (commenting out the parts that change rpmb or flash partitions) and it get's stuck at
    Code:
    [2019-01-28 00:01:40.973289] Disable bootrom range checks

    Does the hash in load_payload.py (4dd12bdf0ec7d26c482490b3482a1b1f) need to be modified?
    I do have the kernel-sources for the device and am willing to investigate correct addressing etc.

    Also since this is a boot-rom exploit wouldn't it allow flashing a hacked preloader + lk which just ignore boot-signatures so we can just run a standard twrp?

    So first of all make sure you're accessing bootrom mode and not preloader mode (Although if the preloader supports read/write, the exploit should work there as well, I just haven't tested it since on hd 8 8th gen none of preloaders support these). I suggest soldering on a UART adapter, then use 115200 baud rate. When in bootrom dl mode, you should see "[DL] 00000BB8 444C0005 010701" (basically, the "[DL]" part is the important one)

    If it's a different soc, you will have to dump the bootrom and find the offset where range check data is stored (in my case, 0x102868). You might have to modify the 4dd12bdf0ec7d26c482490b3482a1b1f part as well, it's basically calculated as a xor of expected data and actual data it's written. Then, you'll also need to update the pointer I'm overwriting (0x1028A8 in my case, called ptr_send in brom-payload). Again, if executing under preloader it's gonna be completely different way to exploit it.

    Once all this is done, you should be able to load binary payloads and execute them in bootrom mode. You'll also need to edit brom-payload and set up proper pointers to send_dword/recv_dword/etc, these can be found by reversing your bootrom dump. At this point it should be possible to get emmc read/write.

    Finally, if you want a persistent unlock (and not just the ability to modify /system) you'll need to port lk exploit as well. So you'll have to figure if your lk is vulnerable to the same bug, port microloader, inject_microloader.py and lk-payload to use the proper offsets. It's a lot of work.

    I'll hopefully finish my writeup in the next weeks and post a link to it, that should be easier to understand since I'll explain the whole process from start to finish.

    You're right about being able to load a custom preloader/lk, however the bootrom exploit requires a PC connection and a bunch of USB commands (so in a way, it's "tethered"). The actual unlock exploit isn't using any bootrom bugs, but rather the lk bug, since that one works without a PC. In fact, the bootrom exploit is only used to flash stuff to eMMC (but, of course you could probably do more fun stuff with it) in my chain.