Fire HD 8 (2018 ONLY) unbrick, downgrade, unlock & root
- Thread starter xyz`
- Start date
From first post
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 )
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:
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 )
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:
Pretty sure you have one that doesnt have bootrom access. Serial mismatch is the preloader mode. You have to be in bootrom mode. It was blocked for unlocking Jannuary 2020.
i think the serial number will identify. you would have to look through the posts it was either covered in this thread or one of the other unlock threads for 2018 hd8. If you are only getting preloader, when shorting likely it is blocked. lsusb will tell you what mode it is in. bootrom comes up as a mediatek phone. @jenka063
should be like the last few digits of the serial number if i remember. if it ends in a 0, you're SOL....
Your can copy files over, not sure how to anymore, but I have done it, easier to unlock and do it from twrp if you get into bootrom.
Read the script files from the bootrom-step, I believe that will tell you how it's doing it.
you might be able to with the SP flash tool
It's now easy to bypass MediaTek's SP Flash Tool authentication
A group of developers has created a Python utility to bypass the authentication routine of MediaTek SP Flash Tool. Check it out now!
I have successfully unlocked the bootloader of my HD8 8th gen running 7.3.2.3 using back cover opened method. Just wanna share with you guys some errors that I could managed to overcome.
1. Stuck at "Wating for bootrom" on Ubuntu 22.4 live
I have tried every possible ways doing exactly every steps mentioned but got no luck to pass the "Waiting for bootrom" step. Have switched different PCs cables but nothing work.
Solution: Used the FireISO 2.0.0 booted with my USB thumb and vola, work immediately.
2. Stuck at "Serial mismatch" error at "bootrom-step.sh"
Some people said this error is due to blocked bootloader. But in my case it's not true.
Solution: Tried with a different usb cables and one of them let me get through. So it was really cable issue in my case.
3. LineageOS 20 stuck at Amazon logo
This was due to the old TWRP version packed with this tutorial.
Solution: Upgrade to newer version of amonet-karnak-v3.0.1 from this thread:
xdaforums.com
Hop this can help anyone facing similar issues.
1. Stuck at "Wating for bootrom" on Ubuntu 22.4 live
I have tried every possible ways doing exactly every steps mentioned but got no luck to pass the "Waiting for bootrom" step. Have switched different PCs cables but nothing work.
Solution: Used the FireISO 2.0.0 booted with my USB thumb and vola, work immediately.
2. Stuck at "Serial mismatch" error at "bootrom-step.sh"
Some people said this error is due to blocked bootloader. But in my case it's not true.
Solution: Tried with a different usb cables and one of them let me get through. So it was really cable issue in my case.
3. LineageOS 20 stuck at Amazon logo
This was due to the old TWRP version packed with this tutorial.
Solution: Upgrade to newer version of amonet-karnak-v3.0.1 from this thread:
[UNLOCK][ROOT][TWRP][UNBRICK] Fire HD 8 2018 (karnak) amonet-3
Read this whole guide before starting. This is for the 8th gen Fire HD8 (karnak). Current version: amonet-karnak-v3.0.1.zip This is based on xyz`s original work, but adds some features such as reboot to hacked BL. It also intends to simplify...
xdaforums.com
Hop this can help anyone facing similar issues.
The above was posted May 6, 2021. Unfortunately, the follow-up just says "I fixed it".
I am having exactly the same issue - can't install "lk". I've tried it several times, with variations on clearing memory segments etc, but I still get the same result. Any help would be much appreciated.
-------
I also found this comment - "Flash lineage.... Have you tried rebooting (reboot recovery). You dont need to install 6300 once you have TWRP installed you can install any rom."
Is this correct? As I am aiming to put Lineage on the tablet, does that mean once I have TWRP on (which I do), I don't need to install anything else? (other than the lineage image, of course?)
-- Follow-up ---
This was answered here...
[UNLOCK][ROOT][TWRP][UNBRICK] Fire HD 8 2018 (karnak) amonet-3
Read this whole guide before starting. This is for the 8th gen Fire HD8 (karnak). Current version: amonet-karnak-v3.0.1.zip This is based on xyz`s original work, but adds some features such as reboot to hacked BL. It also intends to simplify...
xdaforums.com
(see posts #1,101 and #1,103 - 27 Feb 2024)
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Changelog:
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:
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:
Another way to fix a brick:
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 work21GPL 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
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?7OK, 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
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.
