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james508959

New member
May 28, 2021
4
0
thx so much for your detailed reply!
So it seems I must have done something wrong...

After I unlocked bootloader, I cannot get into download mode, it only showed download mode for a brief moment, then it showed that the phone failed some safety test, showed the link: g.co/ABH and after a while it reboot into fastboot mode.

Maybe it's beacause I use fastboot to flash the patched magisk boot.img, instead of using QFIL?

Also, did you followed the simple 4 steps or the original many-steps guide to get finpgerprint working? I only did the 4 steps, because I'm not sure how to safely re-lock the bootloader. I assume the phone need to be at stock everything? EDL mode is kinda scary lol

The earliest KDZ I could find is 10b, I think the phone at first shipped with 10a when it just hit the market, but I could not find 10a kdz anywhere.

I will maybe try 20a twn kdz (seems like a long shot tho) and 10c eu kdz, hopefully something will work!

thx again.
 

zdanee

Senior Member
Sep 27, 2012
89
18
thx so much for your detailed reply!
So it seems I must have done something wrong...

After I unlocked bootloader, I cannot get into download mode, it only showed download mode for a brief moment, then it showed that the phone failed some safety test, showed the link: g.co/ABH and after a while it reboot into fastboot mode.

Maybe it's beacause I use fastboot to flash the patched magisk boot.img, instead of using QFIL?

Also, did you followed the simple 4 steps or the original many-steps guide to get finpgerprint working? I only did the 4 steps, because I'm not sure how to safely re-lock the bootloader. I assume the phone need to be at stock everything? EDL mode is kinda scary lol

The earliest KDZ I could find is 10b, I think the phone at first shipped with 10a when it just hit the market, but I could not find 10a kdz anywhere.

I will maybe try 20a twn kdz (seems like a long shot tho) and 10c eu kdz, hopefully something will work!

thx again.
I flashed everything with QFIL, not fastboot. You can get into download mode even when the phone is unable to boot properly. If you can get into EDL mode try to restore your unpatched boot_a with QFIL and try again! I know it looks scary, but it's also the tool you can bring back even a completely bricked phone as long as you have the backups.
I followed the new, 4 step method for the fingerprint, I did not re-lock the bootloader.
 

kgirlx

Senior Member
Nov 26, 2010
376
94
Is there an update for magisk patch image for 20b (unlocked US variant)?

Edit: Got my 20b version rooted.
Downloaded stock rom for the G850QM20b, extracted the kdz file to dz to .img grabbed the stock boot_a.img file and ran it in Magisk manager app, took the converted .boot.a.img (now renamed magisk_patched_clT14.img) and dropped it in platform tools, went fast boot, then flashed it. Came back up great, no issues and root access is clear.
Could you please share your patched boot.img file for stock US unlocked... I'm thinking of getting this phone and any help is appreciated. Thanks
 

zdanee

Senior Member
Sep 27, 2012
89
18
Could you please share your patched boot.img file for stock US unlocked... I'm thinking of getting this phone and any help is appreciated. Thanks
I would advise to make your own patched boot.img, it's easy to mess up the audio or the fingerprint reader with a boot.img not meant for your device. Making your own is easy too: you install Magisk Manager on your phone, while doing the bootloader unlocking tutorial you save your boot_a with QFIL, reboot the phone, put the boot_a into magisk manager and patch it that way, then once again using QFIL load your very own 100%-guaranteed-for-your-phone boot.img.
 
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Buzzy42

Senior Member
Jul 25, 2014
106
28
I just got the US Unlocked G8X (G850QM) and am really confused about where to start, since a lot of the guides seem to assume you're starting from a 20 Android 10 ROM.

Mine came with Android 9 (G850QM10C). I am confused about all of the people saying if you unlock the bootloader, you will lose fingerprint, but some people say you can roll back to Android 9, and some say that you can just fix it by using your own boot.img that you can patch. I'm confused because it seems like different threads lead to different conclusions.

If I just unlocked the bootloader while I'm still on 10C (Android 9), would that bypass the problems? and then I can update it using the 20e KDZ? (how do you do that and not lose root? Or do you lose root and you just have to re-do it?)

Or should I let it update to the latest OTA, and then start the bootloader unlock and root process, patching my own boot.img, and it should work ok?

Basically, I only want to root it at this point if I can keep the fingerprint reader (and all the other functionality of the phone)

Thanks for help!
 

zdanee

Senior Member
Sep 27, 2012
89
18
I just got the US Unlocked G8X (G850QM) and am really confused about where to start, since a lot of the guides seem to assume you're starting from a 20 Android 10 ROM.

Mine came with Android 9 (G850QM10C). I am confused about all of the people saying if you unlock the bootloader, you will lose fingerprint, but some people say you can roll back to Android 9, and some say that you can just fix it by using your own boot.img that you can patch. I'm confused because it seems like different threads lead to different conclusions.

If I just unlocked the bootloader while I'm still on 10C (Android 9), would that bypass the problems? and then I can update it using the 20e KDZ? (how do you do that and not lose root? Or do you lose root and you just have to re-do it?)

Or should I let it update to the latest OTA, and then start the bootloader unlock and root process, patching my own boot.img, and it should work ok?

Basically, I only want to root it at this point if I can keep the fingerprint reader (and all the other functionality of the phone)

Thanks for help!
The rooting process is basically made up of 3 parts:
- unlocking the bootloader
(- if the fingerprint reader is broken, KDZ to Android 9)
- gaining access to your boot.img
- patching you boot.img

You will loose rooting between major updates, but you won't loose the open bootloader that makes rooting possible.

Some people suggest the fingerprint reader only has a problem if you have a fingerprint enrolled in it before starting the process, so to be on the safe side, delete all your enrolled fingerprints before starting.

You can do the rooting on Android 9, but then when you upgrade to Android 10 you might loose it, as the new image also has a new boot.img that you didn't patch before (if it were patched it would fail the cheksum test and would not install), so you'll probably have to do the rooting after a major update.

Before you start the process try to get ready, download all the tools, images you might need and make backups! You'll need:
- LGUP tool 1.17
- your KDZ for the earliest version you can get from LG-roms
- the latest KDZ you plan to actually use
- LG Drivers and ADB
- QFIL
- a patched abl_a file
- Magisk Manager

You also want a reasonably stable Windows PC you trust not to freeze during flashing and an USB-C cable you trust to work well.

1. I would advise to start straight with the newest ROM you can find, just because you'll have to use less the scary QFIL-mode. Remember: you'll have to patch the boot_a.img from the Android version you want to use, so probably Android 10. So, do all the software upgrades before you start. Or, you can try with your current version, and have the extra step to get your boot_a.img at a later point.

2. Next you do the bootloader unlocking (#3): https://forum.xda-developers.com/t/...el-for-lg-g8-kor-g820n.4228257/#post-85143941

3. While you do the abl_a backup, make sure to also back up your boot_a, if you are on the Android version you plan to use. Check if your audio, network and fingerprint reader still works. If it does, skip the next part.

3.1: so something does not seem to work. You'll have to downgrade to Android 9 to fix it. Using LGUP 1.17 and the KDZ you downloaded earlier downgrade to Android 9 (just use LGUP 1.17 and the KDZ) and do the 4-step simplified fix: https://forum.xda-developers.com/t/...ng-with-unlocked-bootloader-and-root.4202287/
It's possible your earliest version of Android 9 is different from the guide, or that it won't work for that version. In that case download the next earliest version and try again. For my EU Hungarian T-mobile phone it was the 10d version that eventually worked.
3.2: now that everything works time to use LGUP again and upgrade to the latest version. Use KDZ, don't try to upgrade from within Android! Your unlocked bootloder will still work despite the reflashes.

If you are doing this on Android 9, then you have to use LGUP 1.17 and flash your latest KDZ at this point, go back to QFIL and make a backup of boot_a.img at this point.

4: Now you have a working phone, unlocked bootloader and the newest Android. Time to install Magisk Manager. Copy the previously saved boot_a.img to the phone and patch it from within Magisk Manager. Using QFIL once again flash the patched img to the phone. Done, that was it, you are rooted. Time for beer!
 
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Buzzy42

Senior Member
Jul 25, 2014
106
28
Thank you!! I will definitely be trying this in the next few days, just need to clear up some time to ensure I'll be able to chase down any issues that might arise although with such clear instructions I am hoping for the best!
 

Buzzy42

Senior Member
Jul 25, 2014
106
28
Worked fantastic! I stayed on Android 9 to do the unlock mostly because I wasn't entirely sure the KDZ I had was the right one and didn't want to get stranded. Ended up to be a good idea, even though I cleared my FP and PIN code, the FP didn't want to work after the unlock. So I went through the test and got it fixed.

Upgraded to Android 10 (which seemed to switch the boot partition from A to B in my case, had to flash MAgisk to B to get it to finally work) and almost everything is perfect! The only weird glitch I am noticing is I can't update Chrome or Webview to the latest versions, everything else upgrades fine but when I try to update them in the store it just pretend to try and then goes right back to showing "Update". Very strange... doubt it's related to all this but who knows.

Very happy to have a fully functional, rooted, unlocked G8X, thanks again!
 
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  • 6
    This Guide will explain how to root your LG G8X

    * Disclaimer*
    * I am not responsible for bricked devices, dead SD cards, thermonuclear war,
    * or you getting fired because the alarm app failed. Please do some research
    * YOU are choosing to make these modifications, and if
    * you blame me in any way for what happens to your device, I will laugh at you.
    *Wait, what? No. Me or somebody else will help you
    Prerequisites
    Unlock phone using the guide here: https://forum.xda-developers.com/t/guide-how-to-unlock-bootloader-of-lg-g8x.4198025/
    Do not restore abl before rooting.
    Magisk Patched Boot (20e, Indian Variant): https://drive.google.com/file/d/1s2A7RUOptXer5LGMtbGV9SKg0kcyL_NP/view?usp=drivesdk

    1. Download the magisk patched boot.

    2. Copy it over to your fastboot directory.

    3. Connect phone in fastboot mode.

    How to put phone to fastboot mode?

    #1: Using Button Combination

    Power off phone, press and hold Vol- and insert usb cable. You’ll be in fastboot

    #2: Using ADB

    Connect phone to pc, enable USB Debugging. Then run this command
    Code:
    adb reboot fastboot

    4. Now run the command
    Code:
    fastboot flash boot Magisk_Patched.img
    fastboot reboot

    5. Download and install Magisk Manager

    6. Done! Your phone is rooted now.

    To restore Network follow the guide in bootloader unlock thread...

    If you have a different G8X variant or are on a different firmware

    1.Backup boot_a or boot_b using QFIL (Partition Manager>Read Data, Check Bootloader unlock guide for more details)

    2. Install Magisk Manager

    3. Click on Install and use Patch image function.

    4. Save the boot image to pc.

    5. Flash it in Fastboot using the command given above.

    Known Issues: FP is broken

    Thankyou :)
    1
    (copypasta'ed from the other thread)

    For those who have yet to do this, I suggest extracting boot_a/b at the same time you flash the abl image. Prior to doing the fastboot oem unlock, use the Magisk patch file option (installed on the same or another device, and doesn't need to be rooted) to create a rooted boot image using adb push/pull. Once you fastboot oem unlock, go back into the bootloader and instead of fastboot flash boot, you can fastboot boot magisk_patched.img.

    Once you go through the setup, you can open Magisk, which will download and install the full Manager app, at which point it will most likely reboot. You will need to fastboot boot again, and you should be able to do a normal Magisk install. I've usually found that as long as the patched boot is of the same Android version and within a few month of the patch level, it'll boot happily enough to do this. Afterwards, you can restore your abl image as you no longer need to use fastboot commands.

    Doing this allows Magisk to save the stock boot image, and also allows you to get OTA updates by restoring the stock image right before any updates. Otherwise you will never be able to do an OTA update as it checks if the boot partition has been modified before installing the updates. Since there are no kdz for the US carrier models, your only other option would be to "brick" your device to try get your carrier's service center to restore a working firmware image.

    -- Starfox
    1
    Is there a magisk patched image for the g850u20i
    1
    I have 20j and I can't even get into edl or fastboot... Can you get into fastboot mode? I've tried adb and button combos
    I cannot.I've tried everything I know to do.I'm so cautious with this phone because I got it at a steal off of eBay and would hate to brick it.
    1
    So my understanding is you can have a rooted phone, but FP will be broken no matter what and possibly audio as well. You can fix this by reinstalling a Pie version from KDZ, fix it then reinstalling a 10, but then the root will be gone (but the bootloader remains unlocked). Is this correct?
    Yes, rooting will be gone and Bootloader remains unlocked forever. You have to root it again in A10