Bootloader Unlock and Root Instruction - No Octoplus Box Required

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cmrntnnr

Senior Member
Jan 11, 2017
272
206
Do you want to bootloader and unlock and root your V35? Do you want to do this yourself? Are you feeling the need for some adventure? If you answered yes to these questions, then you are at the right place. The goal with these instructions is to make the process as smooth and pain-free as possible. These instructions are based upon what I know works through firsthand experience and what I have gathered reading. My experience is with an AT&T branded V350AWM. Others also report success. That said, there can still be problems leading to bricked phone so don’t continue if you are not comfortable with the risk. An unavoidable side-effect of bootloader unlocking is that all data on your phone will be erased. Make a back up if you don’t want to lose it permanently.

This is what you will be doing in a nutshell.

  • Setting the phone into a baseline Oreo conditions
  • Extraction of abl, laf, and boot partititions
  • Installation of the engineering abl and erasing the laf's using QFIL
  • Unlocking the phone
  • Flashing to Pie and maybe Q in the future if you want to update from Oreo
  • Generation and installation of a magisk-patched boot image for root

Upon successful completion, you will have a fresh, bootloader unlocked and rooted phone that is otherwise stock.

Preparation and requirements:

On the hardware side, you will need a PC with MS Windows installed either directly or as a virtual machine and a high quality USB cable designed for data transfer. Older USB 2.0 hardware is preferred when working with LG phones. There is a long list of software to install.

Download and install each of these programs on your PC in the listed order.

You are also going to need some super important supporting files that make all of this magic possible.


Troubleshooting:
These instructions assume that your phone boots normally. Even with that there can still be issues due to software drivers and pc-hardware. They can be broadly summarized as a difficulty getting the computer to recognize and communicate with the phone and vice-versa. They arise frequently. If you encounter difficulties, review these troubleshooting tips compiled and written by @ChazzMatt and taken from his V30 WTF instructions.

  1. Look in your ADB folder on your PC and confirm all known Windows file extensions enabled, https://goo.gl/YxLRG5.
  2. Confirm all Windows hidden files and folders are visible, https://goo.gl/1jBKne.
  3. Confirm USB debugging is on in Developer Options, and your PC has authorization for your phone, https://goo.gl/DgojL9.
  4. Install another version of ADB. Install as close to the root of your hard drive as possible. X:\ADB where X is your hard drive.
  5. Re-install LG mobile drivers, https://is.gd/Jbrvx1.
  6. Try another USB cable.
  7. Installing this Windows driver found attached to this post, (Thanks @gazzacbr and @FZZF) https://goo.gl/CqqNZT.
  8. Install Google USB driver, (Thanks @s0lidsneak) https://goo.gl/z2Tahw.
  9. Try another USB port on your computer or try cheap USB 2.0 hub, https://is.gd/gM1mM0.
  10. Reboot the computer.
  11. Try another computer. (THIS usually solves the problem, https://goo.gl/x637H1. Kudos if you find an an old Win7 PC, https://goo.gl/EaGMhs.)
  12. Master Reset (full reset of phone using hardware buttons), https://goo.gl/N4LcLD. Phone will be reset anyway after bootloader unlock. Doing it prior may fix something preventing the command from working.

Step 1: Setting an Oreo baseline:

The engineering files for bootloader unlock of the V35 phone are designed to work with Oreo. If you are an Pie or Q, it is highly recommended that you flash back to Oreo. For those of you with the common AT&T V350AWM model that is not on Oreo, there are a couple of points to consider

  1. AT&T does not release flashable roms. If you are on AT&T Pie or eventually Q, there is no going back unless of course you take the time to make a backup of the rom itself. That is not covered in this guide nor am I aware of a guide on how to do this.
  2. AT&T sim-locks its branded V35’s and the menu to unlock is specific to the AT&T rom. You should strongly consider purchasing of a sim-unlock code and applying it before flashing another rom!

To set the baseline:
  • If you are already on Oreo perform a master reset. To do this, start by turning the phone off. Then press and hold the power and volume - buttons at the same time until you see the LG logo appear. When the LG log appears, release the power button and then press and hold it again while continuing to press the volume – button. Follow the menus to perform the reset.
  • If you are on Pie or Q, you are going to flash or cross-flash back to Oreo. The kdz's are available for downloaded from https://lg-firmwares.com/lg-lmv350ulm-firmwares/#tab=firmwares. Reports are that roms can be cross-flashed across V35 models with the exception of the Korean V350N. If you are not familiar with the roms, the favored ones are the Google Fi / North American versions for the V350ULM. Down load the latest Oreo version

    To flash the rom, turn the phone off, press and hold the volume – button while connecting it to the computer’s USB. The phone screen should show “Download Mode”. Start-up LGUP on your PC, select the rom kdz, and flash it using “Refurbish”. Do not use any other modes or you will have serious trouble!

Step 2: Partition Extraction, Modification and Bootloader Unlock

  • Enable “OEM Unlock”: Turn on the phone and go through a minimal set-up process. Next go to Settings→ System→ About Phone→ Software info. Repeatedly tap on “Build Number” until you receive a message that you are now a “Developer”. Next go to Next go to Settings→ System→Developer options. Look for “OEM unlock” and flip the switch to on. Exit the “Settings” menus.
  • Boot the phone in EDL 9008 mode: The “button dance” to put the phone into EDL mode requires quick hands. To increase the likelihood of success, take the phone out of any case to expose the volume buttons. With the phone fully booted and turned on, connect it to your computer by USB. Press and hold the power and volume – keys at the same time. The phone will likely take a screenshoot, keep holding the buttons, afterwards it will bring up a reboot countdown message. With one second left, start pressing the volume + button while still keeping the power and volume – buttons pressed. The phone will show a black screen and windows with make its connection sound if you succeeded in reaching ECL mode. Release the button immediately. Look at your computer, you should also see an entry in the Windows Device Manager under “Ports” that reads:
    “Qualcomm HS-USB QDLoader 9008 (COMXX)”
    where XX is the port. The phone will just reboot if you didn’t click the volume + button sufficiently fast. Keep trying, you will eventually succeed. If the screen on the phone does go black and you don't see the phone listed in the Windows Device Manager, then you should check installation of 9008 port driver.
  • Start and configure QFIL: Go to the Start Menu or whatever passes for it on your Windows computer and fire up QFIL. Survey the screen:
    • You should see “Qualcomm HS-USB QDLoader 9008 XX” next to “Select Port…”.
    • There should be small text in the lower right corner that reads “Storage Type:”; Select “ufs”.
    • There is a subheading near the upper left that reads “Select Build Type”. Tick “Flat Build”.
    • Now using the “Browse…” button under the “Select Programmer", navigate to the folder that contains the firehose file, “prog_ufs_firehose_Sdm845_lgev40.elf” and select it.
  • Extract partitions: Click on “Tools” in the menu bar of QFIL. Select “Partition Manager”. You will be asked if you selected the correct firehose. If you did then click OK. A screen will now appear that lists partitions on your phone. Scroll down the list and look for “abl_a”, “laf_a”, “abl_b”, and “laf_b”.
    • Right click on “abl_a”
    • Select “Manage Partition Data”
    • Select “Read Data…”
    • Open a folder and navigate to location where the extracted file is located. The QFIL “Status” output shows the location and filename. On my PC, it reads:
    • “C:\Users\whoiam\AppData\Roaming\Qualcomm\QFIIL\COMPORT_XX\ReadData_ufs_xxxxx.bin” where XX is the port number and the “xxxxx” are details about the partition name. Copy the file to a dedicated folder and rename it “abl_a.img”.
    • Repeat the this process for “laf_a”, “boot_a”, “abl_b”, “laf_b”, and “boot_b” partitions. Note the locations of these files as back-ups and also for the following section on rooting.
  • Use QFIL to get fastboot:
    • Write the engineering abl’s: In QFIL, do the following:
    • Right click on abl_a.
    • Select “Manage Partition Data”
    • Select “Load Image”
    • In the dialog, Navigate to the location of the engineering abl_a.img file you downloaded in the preparation section, select it, and click “Open”.
    Repeat this same procedure for abl_b.
  • Erase laf’s: In QFIL, do the following:
    • Right click on “laf_a”
    • Select “Manage Partition Data”
    • Select “Erase”
    • Confirm that you want to erase
    Repeat for laf_b.
    • Unplug the phone from USB
    • Press and hold the power and volume - buttons until the LG V35 boot logo appears. Allow the phone to reboot.
    • Turn the phone off.
  • Unlock the bootloader:
    • Enter fastboot mode: Hold the volume + button and plug in the USB cable. The phone will boot to a series of menus that include “Start” and “Power off”.
    • Run a command prompt as Administrator. If necessary navigate to the directory where you installed adb.exe and fastboot.exe.
    • Check that the phone communicates with fastboot: Type “fastboot devices” and press enter. It should return details about your device. It reads “LMV350AWMxxxxxxx fastboot” with my phone.
    • Bootloader unlock: Type “fastboot oem unlock”. Congratulations if it reports OK, your phone is now unlocked. If it reports failed then try another USB port on your PC, a better/different cable, and potentially even another PC.
    • Reboot the phone


Step 3: Restore download mode and flash to desired rom:
  • If the current version of Oreo is where you want to be then skip to Step 4.
  • If you want to upgrade to Pie or eventually Q, then you need to restore the laf_a, laf_b, abl_a, and abl_b partitions to recover download mode. It should be clear from what you have done above with QFIL how to do this.
  • Download the kdz of your desired rom. The Google/NAO version of Pie is recommended and available at this link, https://lg-firmwares.com/downloads-file/22230/V350ULM20f_00_NAO_US_OP_0218.
  • To flash the rom, turn the phone off, press and hold the volume – button while connecting it to the computer’s USB. The phone screen should show “Download Mode”. Start-up LGUP on your PC, select the rom kdz, and flash it using “Refurbish”. Do not use any other modes or you will have serious trouble!

Step 4: Install Magisk for Root:
  • Re-enter EDL mode with the above button dance procedure
  • Extract boot_a and boot_b partitions: Click on “Tools” in the menu bar of QFIL. Select “Partition Manager”. You will be asked if you selected the correct firehose. If you did then click OK. A screen will now appear that lists partitions on your phone. Scroll down the list and look "boot_a” and “boot_b”.
  • Generate a Magisk-patched booted image working directly with the phone:
    • Download a stable version of Magisk Manager from the official website: https://forum.xda-developers.com/apps/magisk/official-magisk-v7-universal-systemless-t3473445. It should be saved in the “Download” folder.
    • In Settings, navigate to Apps & Notifications→ Special access → Install unknown apps. Click on File Manager and set it to allowed.
    • Open the “File Manager” app and navigate to the Download folder.
    • Select and install the “MagiskManager-v7.5.1.apk” file keeping in mind that the version numbers may be different.
    • Connect the phone to USB and place it in file transfer mode.
    • Copy boot_a.img and boot_b.img to the phone Download folder
    • Start “MagiskManager” and select “Install”. When presented with the option, tap “Select and Patch a File”.
    • Navigate to the “Downloads” folder where and select boot_a.img.
      There will now be a file named “magisk_patched.img” in the “Downloads” folder. Change its name to magisk_patched_a.img.
      Repeat this process with boot_b.img.
    • Install the Magisk-patched boot images using the PC:
    • Copy the magisk_patched_a.img and magisk_patched_b to the windows computer.
    • Put the phone into 9008 EDL mode with the button dance described above.
    • Start QFIL, configure it as described above, and then click on “Tools” in the menu bar of QFIL and Select “Partition Manager”.
    • Scroll through the list of partitions and locate boot_a. Right click on it and select “Load Image”. Point it to the magisk_patched_a.img file.
    • Repeat the previous step for boot_b and load the magisk_patched_b.img file
  • Reboot your rooted phone.

Step 5: Remove Root Checker: (Added 20200409)

I say with sarcasm that another way that LG has made our lives better was to implement a root-check and monitoring system. Many here are familiar with the root check daemon from the V30. There is a root-check disable twrp package to fix this problem. Installation and use of TWRP for the V35 is tricky. Don't worry, there is another way.

  • Put the phone in USB debug mode
  • Connect to your computer
  • With adb from a command prompt on the computer do the following

    • adb devices <-- If your devices is properly connect and recognized, adb will respond
      List of devices attached
      LMV350XXXXXXXXX device

    • adb shell <-- If you have a shell into the phone you will now see
      judyp:/ $

    • pm uninstall -k --user 0 com.lge.srtc <-- This command removes the root checker, if it succeeds you will get the response:
      Success

    • pm uninstall -k --user 0 com.lge.mlt <-- This command removes the LG monitor, if it succeeds you will get the response:
      Success

Happy Rooting!
 
Last edited:

fpozar

Senior Member
Apr 7, 2016
222
94
Wow,
Thanks for the great guide, can't wait to try this.
One question, though, regarding your cross flashing warning. Where did you get the information that Korean V35 can not cross flash? I own a Korean model and it's kinda annoying to constantly be in roaming mode, I was hoping that ULM will change that. So basically, the best I can do is root, not other rom is okay for LM-V350N?
 

cmrntnnr

Senior Member
Jan 11, 2017
272
206
There are several posts by owners of AT&T branded V35's who cross-flashed to the Korean V350N Pie rom successfully. They were in a rush for Pie and it was released for Korean models first. Still, I have in my notes not to do the reverse, but I can't find the link. Hypothetically, one can recover from about anything using 9008 mode and QFIL provided you have back ups of the partition images of your phone.
Wow,
Thanks for the great guide, can't wait to try this.
One question, though, regarding your cross flashing warning. Where did you get the information that Korean V35 can not cross flash? I own a Korean model and it's kinda annoying to constantly be in roaming mode, I was hoping that ULM will change that. So basically, the best I can do is root, not other rom is okay for LM-V350N?
 

Shawnashley

Senior Member
Oct 21, 2012
133
13
Talking Rock
There are several posts by owners of AT&T branded V35's who cross-flashed to the Korean V350N Pie rom successfully. They were in a rush for Pie and it was released for Korean models first. Still, I have in my notes not to do the reverse, but I can't find the link. Hypothetically, one can recover from about anything using 9008 mode and QFIL provided you have back ups of the partition images of your phone.


I was one of those who leaped to the Korean KDZ. Now I am running NAO firmware. Guide looks well written. I might wind up taking the leap. Good job bro!
 

cmrntnnr

Senior Member
Jan 11, 2017
272
206
Nicely done. Thank yoh for sharing the result.

Wow,
Thanks for the great guide, can't wait to try this.
One question, though, regarding your cross flashing warning. Where did you get the information that Korean V35 can not cross flash? I own a Korean model and it's kinda annoying to constantly be in roaming mode, I was hoping that ULM will change that. So basically, the best I can do is root, not other rom is okay for LM-V350N?

Thanks, I follow your steps very carfully, and now I have a rooted v35.
 
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Iantuition

Member
Jan 12, 2013
43
0
So due to prior.... mishaps, my phone will not boot ("all slots are unbootable!"), and fastboot produces "Flashing Unlock is not allowed" every time the OEM unlock is attempted. What should I do?
 

dave1567

New member
Feb 22, 2020
3
0
I am stuck at Fastboot Mode. It says the "Device state - Unlocked", but when if I choose Start or Power off/on my phone it just goes back into fastboot everytime.

1. I installed and flashed the Pie rom you linked in step 1
2. I turned "Oem unlock" to On.
3. placed the phone in 9008 mode, backed up abl_a, laf_a, boot_a, abl_b, laf_b, and boot_b.
Loaded the img to abl_a and abl_b.
Finally, Erased laf_a and laf_b
4. within fastboot, unlocked bootloader

Any ideas ?
 

cmrntnnr

Senior Member
Jan 11, 2017
272
206
If the phone unlocked, go back into 9008 EDL mode and restore the laf and abl images using your backups. That should get you booting.
 

vlad48

Senior Member
Oct 1, 2007
497
262
LG V35
Any ideas ?
1. Download the attached EDL.zip
2. Extract it to a local folder on your PC
3. While your V35 is in fastboot mode plug it to your PC via USB (USB2 port preferred)
4. Double click on RebootEDL.bat
5. Phone will enter 9008 (EDL) mode screen will be black.
6.Using QFIL flash back your PIE abl_a and abl_b
7. Using QFIL flash attached FTM partition from FTMV35PIE.zip.
8. Hold Vol-and power to reboot.
 

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dave1567

New member
Feb 22, 2020
3
0
1. Download the attached EDL.zip
2. Extract it to a local folder on your PC
3. While your V35 is in fastboot mode plug it to your PC via USB (USB2 port preferred)
4. Double click on RebootEDL.bat
5. Phone will enter 9008 (EDL) mode screen will be black.
6.Using QFIL flash back your PIE abl_a and abl_b
7. Using QFIL flash attached FTM partition from FTMV35PIE.zip.
8. Hold Vol-and power to reboot.

I didn't use your bat since it looks like I can still boot into 9008 mode with the button dance method.
Unfortunately, still nothing!
I flashed my abl_a.img and abl_b.img backups I made to the abl_a/b partitions and flashed your FTM_BL.img to my FTM partition, but it didn't seem to do anything except cause some graphical glitches within fastboot menu (everything still functioned though)

Just in case, I re-locked my phone (fastboot oem lock) and started the QFIL process over (flashing with engineered abl_a and abl_b imgs)
Then within fastboot mode, I ran "fastboot oem unlock" a few times because it fails, but finally it went through
Now the phone is unlocked again, but still just always just boots into fastboot mode!
 

vlad48

Senior Member
Oct 1, 2007
497
262
LG V35
Of course it will boot only to fastboot as you are using engineering abl from Oreo - please understand there is a signature check match which fails and you will not be able to continue booting.
So, in brief, you need to have all partitions on respective bootable slot form either Oreo or Pie kdz version. So you need to be sure that you flashed your PIE abl wither via QFIL or via LGUP.
 

dave1567

New member
Feb 22, 2020
3
0
Of course it will boot only to fastboot as you are using engineering abl from Oreo - please understand there is a signature check match which fails and you will not be able to continue booting.
So, in brief, you need to have all partitions on respective bootable slot form either Oreo or Pie kdz version. So you need to be sure that you flashed your PIE abl wither via QFIL or via LGUP.

Unfortunately, I don't understand. Thanks for trying to help though.

Anyways, I managed to fix the problem and I'm all set.
- Restored my laf_a and laf_b partitions
- Booted into download mode and re-installed the pie image with LG Up.
- Was now able to boot normally
- Followed the instructions in the guide to get magisk installed and now I'm all set!

Thanks all and hope this helps someone
 

Meatmassuse

Member
Aug 22, 2019
10
3
29
Beaverton
I scouted my way through these very same steps a couple weeks ago. Soft bricked my device a couple times ? but eventually got her there. Glad too see a dedicated guide is out now. Only problem I've run into is the ctsprofile:fail problem. Been able to fix with spoof pixel fingerprints but it's not ideal. Still looking for solutions if anyone knows anything.
 

Android#

Senior Member
Apr 18, 2016
158
88
So due to prior.... mishaps, my phone will not boot ("all slots are unbootable!"), and fastboot produces "Flashing Unlock is not allowed" every time the OEM unlock is attempted. What should I do?

What is the minimum needed for you to enter download mode? I have backups of most partitions i will be happy to share and you can use Qfil to flash those to get to download mode then use LGUP to flash a normal kdz? If so, let me know.
 

Flowtron3000

Member
Sep 8, 2015
7
1
so somehow between qfil and getting fastboot i've got myself in trouble. i dont understand what i did wrong but i got stuck in a fastboot loop and tried following some of the fixes mentioned previously in this thread. when i get back to qfil and try to go to partition manager it wont let me see any of the partitions and shows various sahara errors and fails in the log box. can someone please help idk what to do
 

cmrntnnr

Senior Member
Jan 11, 2017
272
206
Sorry to hear that. The first time I tried to use QFIL I got a Sahara error and could not see partitions. It was resolved by reinstalling the 9008 port driver and then QPST in that order. It happened again later when windows tries to be helpful by automatically reinstalling drivers when the phone is plugged in but with a mode change.

so somehow between qfil and getting fastboot i've got myself in trouble. i dont understand what i did wrong but i got stuck in a fastboot loop and tried following some of the fixes mentioned previously in this thread. when i get back to qfil and try to go to partition manager it wont let me see any of the partitions and shows various sahara errors and fails in the log box. can someone please help idk what to do
 

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    Do you want to bootloader and unlock and root your V35? Do you want to do this yourself? Are you feeling the need for some adventure? If you answered yes to these questions, then you are at the right place. The goal with these instructions is to make the process as smooth and pain-free as possible. These instructions are based upon what I know works through firsthand experience and what I have gathered reading. My experience is with an AT&T branded V350AWM. Others also report success. That said, there can still be problems leading to bricked phone so don’t continue if you are not comfortable with the risk. An unavoidable side-effect of bootloader unlocking is that all data on your phone will be erased. Make a back up if you don’t want to lose it permanently.

    This is what you will be doing in a nutshell.

    • Setting the phone into a baseline Oreo conditions
    • Extraction of abl, laf, and boot partititions
    • Installation of the engineering abl and erasing the laf's using QFIL
    • Unlocking the phone
    • Flashing to Pie and maybe Q in the future if you want to update from Oreo
    • Generation and installation of a magisk-patched boot image for root

    Upon successful completion, you will have a fresh, bootloader unlocked and rooted phone that is otherwise stock.

    Preparation and requirements:

    On the hardware side, you will need a PC with MS Windows installed either directly or as a virtual machine and a high quality USB cable designed for data transfer. Older USB 2.0 hardware is preferred when working with LG phones. There is a long list of software to install.

    Download and install each of these programs on your PC in the listed order.

    You are also going to need some super important supporting files that make all of this magic possible.


    Troubleshooting:
    These instructions assume that your phone boots normally. Even with that there can still be issues due to software drivers and pc-hardware. They can be broadly summarized as a difficulty getting the computer to recognize and communicate with the phone and vice-versa. They arise frequently. If you encounter difficulties, review these troubleshooting tips compiled and written by @ChazzMatt and taken from his V30 WTF instructions.

    1. Look in your ADB folder on your PC and confirm all known Windows file extensions enabled, https://goo.gl/YxLRG5.
    2. Confirm all Windows hidden files and folders are visible, https://goo.gl/1jBKne.
    3. Confirm USB debugging is on in Developer Options, and your PC has authorization for your phone, https://goo.gl/DgojL9.
    4. Install another version of ADB. Install as close to the root of your hard drive as possible. X:\ADB where X is your hard drive.
    5. Re-install LG mobile drivers, https://is.gd/Jbrvx1.
    6. Try another USB cable.
    7. Installing this Windows driver found attached to this post, (Thanks @gazzacbr and @FZZF) https://goo.gl/CqqNZT.
    8. Install Google USB driver, (Thanks @s0lidsneak) https://goo.gl/z2Tahw.
    9. Try another USB port on your computer or try cheap USB 2.0 hub, https://is.gd/gM1mM0.
    10. Reboot the computer.
    11. Try another computer. (THIS usually solves the problem, https://goo.gl/x637H1. Kudos if you find an an old Win7 PC, https://goo.gl/EaGMhs.)
    12. Master Reset (full reset of phone using hardware buttons), https://goo.gl/N4LcLD. Phone will be reset anyway after bootloader unlock. Doing it prior may fix something preventing the command from working.

    Step 1: Setting an Oreo baseline:

    The engineering files for bootloader unlock of the V35 phone are designed to work with Oreo. If you are an Pie or Q, it is highly recommended that you flash back to Oreo. For those of you with the common AT&T V350AWM model that is not on Oreo, there are a couple of points to consider

    1. AT&T does not release flashable roms. If you are on AT&T Pie or eventually Q, there is no going back unless of course you take the time to make a backup of the rom itself. That is not covered in this guide nor am I aware of a guide on how to do this.
    2. AT&T sim-locks its branded V35’s and the menu to unlock is specific to the AT&T rom. You should strongly consider purchasing of a sim-unlock code and applying it before flashing another rom!

    To set the baseline:
    • If you are already on Oreo perform a master reset. To do this, start by turning the phone off. Then press and hold the power and volume - buttons at the same time until you see the LG logo appear. When the LG log appears, release the power button and then press and hold it again while continuing to press the volume – button. Follow the menus to perform the reset.
    • If you are on Pie or Q, you are going to flash or cross-flash back to Oreo. The kdz's are available for downloaded from https://lg-firmwares.com/lg-lmv350ulm-firmwares/#tab=firmwares. Reports are that roms can be cross-flashed across V35 models with the exception of the Korean V350N. If you are not familiar with the roms, the favored ones are the Google Fi / North American versions for the V350ULM. Down load the latest Oreo version

      To flash the rom, turn the phone off, press and hold the volume – button while connecting it to the computer’s USB. The phone screen should show “Download Mode”. Start-up LGUP on your PC, select the rom kdz, and flash it using “Refurbish”. Do not use any other modes or you will have serious trouble!

    Step 2: Partition Extraction, Modification and Bootloader Unlock

    • Enable “OEM Unlock”: Turn on the phone and go through a minimal set-up process. Next go to Settings→ System→ About Phone→ Software info. Repeatedly tap on “Build Number” until you receive a message that you are now a “Developer”. Next go to Next go to Settings→ System→Developer options. Look for “OEM unlock” and flip the switch to on. Exit the “Settings” menus.
    • Boot the phone in EDL 9008 mode: The “button dance” to put the phone into EDL mode requires quick hands. To increase the likelihood of success, take the phone out of any case to expose the volume buttons. With the phone fully booted and turned on, connect it to your computer by USB. Press and hold the power and volume – keys at the same time. The phone will likely take a screenshoot, keep holding the buttons, afterwards it will bring up a reboot countdown message. With one second left, start pressing the volume + button while still keeping the power and volume – buttons pressed. The phone will show a black screen and windows with make its connection sound if you succeeded in reaching ECL mode. Release the button immediately. Look at your computer, you should also see an entry in the Windows Device Manager under “Ports” that reads:
      “Qualcomm HS-USB QDLoader 9008 (COMXX)”
      where XX is the port. The phone will just reboot if you didn’t click the volume + button sufficiently fast. Keep trying, you will eventually succeed. If the screen on the phone does go black and you don't see the phone listed in the Windows Device Manager, then you should check installation of 9008 port driver.
    • Start and configure QFIL: Go to the Start Menu or whatever passes for it on your Windows computer and fire up QFIL. Survey the screen:
      • You should see “Qualcomm HS-USB QDLoader 9008 XX” next to “Select Port…”.
      • There should be small text in the lower right corner that reads “Storage Type:”; Select “ufs”.
      • There is a subheading near the upper left that reads “Select Build Type”. Tick “Flat Build”.
      • Now using the “Browse…” button under the “Select Programmer", navigate to the folder that contains the firehose file, “prog_ufs_firehose_Sdm845_lgev40.elf” and select it.
    • Extract partitions: Click on “Tools” in the menu bar of QFIL. Select “Partition Manager”. You will be asked if you selected the correct firehose. If you did then click OK. A screen will now appear that lists partitions on your phone. Scroll down the list and look for “abl_a”, “laf_a”, “abl_b”, and “laf_b”.
      • Right click on “abl_a”
      • Select “Manage Partition Data”
      • Select “Read Data…”
      • Open a folder and navigate to location where the extracted file is located. The QFIL “Status” output shows the location and filename. On my PC, it reads:
      • “C:\Users\whoiam\AppData\Roaming\Qualcomm\QFIIL\COMPORT_XX\ReadData_ufs_xxxxx.bin” where XX is the port number and the “xxxxx” are details about the partition name. Copy the file to a dedicated folder and rename it “abl_a.img”.
      • Repeat the this process for “laf_a”, “boot_a”, “abl_b”, “laf_b”, and “boot_b” partitions. Note the locations of these files as back-ups and also for the following section on rooting.
    • Use QFIL to get fastboot:
      • Write the engineering abl’s: In QFIL, do the following:
      • Right click on abl_a.
      • Select “Manage Partition Data”
      • Select “Load Image”
      • In the dialog, Navigate to the location of the engineering abl_a.img file you downloaded in the preparation section, select it, and click “Open”.
      Repeat this same procedure for abl_b.
    • Erase laf’s: In QFIL, do the following:
      • Right click on “laf_a”
      • Select “Manage Partition Data”
      • Select “Erase”
      • Confirm that you want to erase
      Repeat for laf_b.
      • Unplug the phone from USB
      • Press and hold the power and volume - buttons until the LG V35 boot logo appears. Allow the phone to reboot.
      • Turn the phone off.
    • Unlock the bootloader:
      • Enter fastboot mode: Hold the volume + button and plug in the USB cable. The phone will boot to a series of menus that include “Start” and “Power off”.
      • Run a command prompt as Administrator. If necessary navigate to the directory where you installed adb.exe and fastboot.exe.
      • Check that the phone communicates with fastboot: Type “fastboot devices” and press enter. It should return details about your device. It reads “LMV350AWMxxxxxxx fastboot” with my phone.
      • Bootloader unlock: Type “fastboot oem unlock”. Congratulations if it reports OK, your phone is now unlocked. If it reports failed then try another USB port on your PC, a better/different cable, and potentially even another PC.
      • Reboot the phone


    Step 3: Restore download mode and flash to desired rom:
    • If the current version of Oreo is where you want to be then skip to Step 4.
    • If you want to upgrade to Pie or eventually Q, then you need to restore the laf_a, laf_b, abl_a, and abl_b partitions to recover download mode. It should be clear from what you have done above with QFIL how to do this.
    • Download the kdz of your desired rom. The Google/NAO version of Pie is recommended and available at this link, https://lg-firmwares.com/downloads-file/22230/V350ULM20f_00_NAO_US_OP_0218.
    • To flash the rom, turn the phone off, press and hold the volume – button while connecting it to the computer’s USB. The phone screen should show “Download Mode”. Start-up LGUP on your PC, select the rom kdz, and flash it using “Refurbish”. Do not use any other modes or you will have serious trouble!

    Step 4: Install Magisk for Root:
    • Re-enter EDL mode with the above button dance procedure
    • Extract boot_a and boot_b partitions: Click on “Tools” in the menu bar of QFIL. Select “Partition Manager”. You will be asked if you selected the correct firehose. If you did then click OK. A screen will now appear that lists partitions on your phone. Scroll down the list and look "boot_a” and “boot_b”.
    • Generate a Magisk-patched booted image working directly with the phone:
      • Download a stable version of Magisk Manager from the official website: https://forum.xda-developers.com/apps/magisk/official-magisk-v7-universal-systemless-t3473445. It should be saved in the “Download” folder.
      • In Settings, navigate to Apps & Notifications→ Special access → Install unknown apps. Click on File Manager and set it to allowed.
      • Open the “File Manager” app and navigate to the Download folder.
      • Select and install the “MagiskManager-v7.5.1.apk” file keeping in mind that the version numbers may be different.
      • Connect the phone to USB and place it in file transfer mode.
      • Copy boot_a.img and boot_b.img to the phone Download folder
      • Start “MagiskManager” and select “Install”. When presented with the option, tap “Select and Patch a File”.
      • Navigate to the “Downloads” folder where and select boot_a.img.
        There will now be a file named “magisk_patched.img” in the “Downloads” folder. Change its name to magisk_patched_a.img.
        Repeat this process with boot_b.img.
      • Install the Magisk-patched boot images using the PC:
      • Copy the magisk_patched_a.img and magisk_patched_b to the windows computer.
      • Put the phone into 9008 EDL mode with the button dance described above.
      • Start QFIL, configure it as described above, and then click on “Tools” in the menu bar of QFIL and Select “Partition Manager”.
      • Scroll through the list of partitions and locate boot_a. Right click on it and select “Load Image”. Point it to the magisk_patched_a.img file.
      • Repeat the previous step for boot_b and load the magisk_patched_b.img file
    • Reboot your rooted phone.

    Step 5: Remove Root Checker: (Added 20200409)

    I say with sarcasm that another way that LG has made our lives better was to implement a root-check and monitoring system. Many here are familiar with the root check daemon from the V30. There is a root-check disable twrp package to fix this problem. Installation and use of TWRP for the V35 is tricky. Don't worry, there is another way.

    • Put the phone in USB debug mode
    • Connect to your computer
    • With adb from a command prompt on the computer do the following

      • adb devices <-- If your devices is properly connect and recognized, adb will respond
        List of devices attached
        LMV350XXXXXXXXX device

      • adb shell <-- If you have a shell into the phone you will now see
        judyp:/ $

      • pm uninstall -k --user 0 com.lge.srtc <-- This command removes the root checker, if it succeeds you will get the response:
        Success

      • pm uninstall -k --user 0 com.lge.mlt <-- This command removes the LG monitor, if it succeeds you will get the response:
        Success

    Happy Rooting!
    4
    It is great to see people unlocking their V35's.
    It is disheartening to hear so many problems. I'll make updates to the original post. I've been taking notes where people have had difficulty and want to make sure that I pull in as much as possible. Thank you @larciel for the list of improvements, @Android# for guiding others through this journey and others not named. I'll be making changes to the OP to hopefully make this process smoother.

    The biggest source of avoidable difficulty seems to be with Pie. The guidance will be to flash last stable Oreo kdz and then upgrade to Pie afterwards.

    I am at a loss about what to suggest regarding PC's, software, and cables. Digging out an old PC from the closet, basement, or attic just doesn't seem helpful. LG phones like USB 2.0. It is not easy to tell a good cable from a bad one. The Windows handling of drivers is an utter nightmare. I agree with @asltLies comment aboit this and feel your pain. Personally I have used an old Win7 laptop that never connects to the internet.

    A potential side effect of driver and cable issues is that Qfil appears to work but gives corrupt backup files. I will post md5 sums to use as verification.

    One especially irritating problem is inability to get back to download mode regardless of the cause or symptoms. Being able to blast the problems away by flashing a kdz is reassuring and anxiety provoking if lost. Download mode functionality resides within laf. Just as there is an engineering abl that gives fastboot function, there is an engineering laf at this link.

    https://www.androidfilehost.com/?fid=1395089523397937620

    It can be written with qfil and has helped get me out of some pinches. Perhaps it will do the same for others.
    3
    There are several posts by owners of AT&T branded V35's who cross-flashed to the Korean V350N Pie rom successfully. They were in a rush for Pie and it was released for Korean models first. Still, I have in my notes not to do the reverse, but I can't find the link. Hypothetically, one can recover from about anything using 9008 mode and QFIL provided you have back ups of the partition images of your phone.
    Wow,
    Thanks for the great guide, can't wait to try this.
    One question, though, regarding your cross flashing warning. Where did you get the information that Korean V35 can not cross flash? I own a Korean model and it's kinda annoying to constantly be in roaming mode, I was hoping that ULM will change that. So basically, the best I can do is root, not other rom is okay for LM-V350N?
    3
    The biggest source of avoidable difficulty seems to be with Pie. The guidance will be to flash last stable Oreo kdz and then upgrade to Pie afterwards.

    Sure, sort of like how you need early Oreo for V30. I know it's not the same situation, but it's an analogy.

    If people say the procedure isn't working, first ask what firmware they are on. ;)


    I am at a loss about what to suggest regarding PC's, software, and cables. Digging out an old PC from the closet, basement, or attic just doesn't seem helpful. LG phones like USB 2.0. It is not easy to tell a good cable from a bad one. The Windows handling of drivers is an utter nightmare.

    Personally I have used an old Win7 laptop that never connects to the internet.

    In a similar vein, I give you permission to copy and adapt my V30 WTF Section 7 Trouble Shooting Tips for the V35. I even have links to different resources in those tips.

    There's a dozen tips. First one is firmware version. The other 11 deal with ADB/fastboot communication issues. Reinstall drivers, different port, different cable, different ADB installation, different computer. Bonus points for old Win7 Intel PC with USB 2.0. Also people have used cheap USB 2.0 hub. All that is in my Section 7 Trouble Shooting Tips.

    Already written out and when people ask for help, point them to that first. Of course your version incorporating some V35 points. You can post it bottom of your instructions. Just say "adapted from @ChazzMatt Trouble Shooting Tips for V30". ;)
    3
    I
    <snip>
    One especially irritating problem is inability to get back to download mode regardless of the cause or symptoms. Being able to blast the problems away by flashing a kdz is reassuring and anxiety provoking if lost. Download mode functionality resides within laf. Just as there is an engineering abl that gives fastboot function, there is an engineering laf at this link.

    https://www.androidfilehost.com/?fid=1395089523397937620

    It can be written with qfil and has helped get me out of some pinches. Perhaps it will do the same for others.

    And, in a way, we've come full circle :) What I mean is, that engineering laf, like the abl, is for Oreo :)
    I say that because I tried it and didn't work for me on Pie, so I'm assuming it's Oreo like the engineering abl?

    A word of caution re re-doing the instructions; Keep it simple. I find, as I'd bet others have also, when instructions get more and more verbose, when they start yelling DON'T DO THIS!!! and DON'T DO THAT!!!! in big red letters no less, it just adds more stress to something that's already stressful enough.

    There's just no amount of words, or how you say them (or scream them), that will keep mistakes from happening, it's just not possible. But vice versa, when viewing page after page after page of verbose instructions and yelling, that try to cover every conceivable issue that ever existed, some will just say 'screw this I've better things to do'.

    kiss. U know what I mean. Modify slightly what you have to fix obvious errors / omissions, sure, but don't write a book. Anybody worth their salt will read the rest of the posts to fill in any gaps if they have any.

    Cheers, hope you don't mind the suggestion, and thanks again.
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