I bricked my LG V40 (ATnT variant) and dont know what to do to get it back

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hkguy80

Member
Oct 31, 2012
22
2
good. Yes the best way, especially with korean rom, is to flash the v35 eng abl to your not active slot, which I think in your case is 'b', so abl_b.

the key to that working is you need to have twrp installed, so you can use it to set 'b' partition as active, then select 'reboot bootloader' and it will boot to fastboot. You can then use fastboot and follow the info in this vbmeta link. Read the directions.

the other option (if u don't have twrp yet), would be to flash v35 eng to a, boot to fastboot, do the vbmeta stuff, then use fastboot to flash the original abl_a back, so it will boot.
Either way, I will backup the original abl_a and abl_b before flashing. It is really scary to brick a phone.

Thanks for your help again!!!!
 
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hkguy80

Member
Oct 31, 2012
22
2
good. Yes the best way, especially with korean rom, is to flash the v35 eng abl to your not active slot, which I think in your case is 'b', so abl_b.

the key to that working is you need to have twrp installed, so you can use it to set 'b' partition as active, then select 'reboot bootloader' and it will boot to fastboot. You can then use fastboot and follow the info in this vbmeta link. Read the directions.

the other option (if u don't have twrp yet), would be to flash v35 eng to a, boot to fastboot, do the vbmeta stuff, then use fastboot to flash the original abl_a back, so it will boot.
The first method is not worked me as I cannot boot into fastboot or bootloader. I cannot flash the twrp in via bootloader or fastboot.

The 2nd method also not working. After i issued the command , it stated:
" Sending 'vbmeta_a' (4 KB) FAILED (Write to device failed (Invalid argument)) "

Should I downgrade the Android to Pie or Oreo. Then, try to unlock the bootloader and root again?

Since the seller already unlocked bootloader on my phone, can I backup the unlock.bin from QFIL before downgrading to avoid requesting unlock bootloader from LG again?

Thanks!
 
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AsItLies

Senior Member
Nov 4, 2009
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tucson
The first method is not worked me as I cannot boot into fastboot or bootloader. I cannot flash the twrp in via bootloader or fastboot.

The 2nd method also not working. After i issued the command , it stated:
" Sending 'vbmeta_a' (4 KB) FAILED (Write to device failed (Invalid argument)) "

Should I downgrade the Android to Pie or Oreo. Then, try to unlock the bootloader and root again?

Since the seller already unlocked bootloader on my phone, can I backup the unlock.bin from QFIL before downgrading to avoid requesting unlock bootloader from LG again?

Thanks!

okay, because you don't yet have twrp, when I said flash v35 eng abl, I meant exactly as you've done it already, with qfil. It's the only option you have that will work.

as i said, read the directions that comes with vbmeta folder. It states the command specifically. It's important.

don't downgrade anything. Once the bootloader is unlocked, it won't 'relock', not possible. And no, there is no 'unlock.bin' for these phones, so nothing to back-up.
 

hkguy80

Member
Oct 31, 2012
22
2
okay, because you don't yet have twrp, when I said flash v35 eng abl, I meant exactly as you've done it already, with qfil. It's the only option you have that will work.

as i said, read the directions that comes with vbmeta folder. It states the command specifically. It's important.

don't downgrade anything. Once the bootloader is unlocked, it won't 'relock', not possible. And no, there is no 'unlock.bin' for these phones, so nothing to back-up.
After I flashed the v35 eng abl and reboot the phone with pressing vol - button, the phone entered the fastboot mode. Then, I copy and paste your command. The following result appeared.
Is there anything I miss?

1619373776671.png
 

AsItLies

Senior Member
Nov 4, 2009
981
426
tucson
After I flashed the v35 eng abl and reboot the phone with pressing vol - button, the phone entered the fastboot mode. Then, I copy and paste your command. The following result appeared.
Is there anything I miss?

View attachment 5290331

did u put in all those ?'s ? or does fastboot not recognize the device? I have no way to know.

try this do 'fastboot getvar all' and if u get good output, then the driver is working, if not, it's a driver problem.

also, when you use that command, the part 'blank_vbmenta.img' should include the path to where the image is! If it's in the 'current directory' on your pc, then it will find it, but if it's in some other directory, you have to indicate that in the command.
 

hkguy80

Member
Oct 31, 2012
22
2
did u put in all those ?'s ? or does fastboot not recognize the device? I have no way to know.

try this do 'fastboot getvar all' and if u get good output, then the driver is working, if not, it's a driver problem.

also, when you use that command, the part 'blank_vbmenta.img' should include the path to where the image is! If it's in the 'current directory' on your pc, then it will find it, but if it's in some other directory, you have to indicate that in the command.
Can you advice which driver i should used with the v35 eng abl fastboot?
 

AsItLies

Senior Member
Nov 4, 2009
981
426
tucson
Can you advice which driver i should used with the v35 eng abl fastboot?
you need the lg usb drivers for (whatever) OS you're using, probably windows?

there isn't a specific driver for the v35 eng abl, there is a driver for lg phones for usb connections, to enable fastboot and adb.
 

hkguy80

Member
Oct 31, 2012
22
2
you need the lg usb drivers for (whatever) OS you're using, probably windows?

there isn't a specific driver for the v35 eng abl, there is a driver for lg phones for usb connections, to enable fastboot and adb.
Hi,

Since I am still not able to flash file in fast boot, I try search the reason for that from Internet. Then, I found that someone on Internet said that the fastboot of v409n is read only. He suggest to flash the v409N to android 10 30f first.
Then flash the boot-twrp-30f_a.img that you provided to boot_a via QFIL and then install "Disable_Dm-Verity_ForceEncrypt_03.04.2020.zip" via TWRP.
And then root the v409N via Magisk.
Then, I should able to copy the open_US to oem folder.

Do you think this is an possible way to replace the OPEN_KR?

Thanks a lot.
 
Last edited:

AsItLies

Senior Member
Nov 4, 2009
981
426
tucson
Hi,

Since I am still not able to flash file in fast boot, I try search the reason for that from Internet. Then, I found that someone on Internet said that the fastboot of v409n is read only. He suggest to flash the v409N to android 10 30f first.
Then flash the boot-twrp-30f_a.img that you provided to boot_a via QFIL and then install "Disable_Dm-Verity_ForceEncrypt_03.04.2020.zip" via TWRP.
And then root the v409N via Magisk.
Then, I should able to copy the open_US to oem folder.

Do you think this is an possible way to replace the OPEN_KR?

Thanks a lot.

So need to make sure a few things are clear:

1) there are 2 ways to get fastboot on your device: 1) nuking the laf partition does give a watered down v409 version of fastboot but it's a very weak version. 2) using the v35 eng abl (which is what I thought you were doing), It's the full fastboot version but it won't 'boot' anything because it's Pie, and can only 'boot' Pie partitions.

2) on your device, no matters which fastboot version you use, you'll still need to get windows to recognize the device in fastboot mode, so you still need that driver.

3) Yes, you most definitely would want to flash the boot+twrp using qfil. Then, immediately use the button combo and go to recovery. Once in recovery, format (not wipe) data, then reboot recovery. Then flash magisk and then dm-verity.

4) then, and this is where you need the engineering abl to work, so you have full fastboot, you need to follow the instructions here and flash blank vbmeta. If you don't do this part any changes (like OP folder) won't work.

good luck
 

hkguy80

Member
Oct 31, 2012
22
2
So need to make sure a few things are clear:

1) there are 2 ways to get fastboot on your device: 1) nuking the laf partition does give a watered down v409 version of fastboot but it's a very weak version. 2) using the v35 eng abl (which is what I thought you were doing), It's the full fastboot version but it won't 'boot' anything because it's Pie, and can only 'boot' Pie partitions.

2) on your device, no matters which fastboot version you use, you'll still need to get windows to recognize the device in fastboot mode, so you still need that driver.

3) Yes, you most definitely would want to flash the boot+twrp using qfil. Then, immediately use the button combo and go to recovery. Once in recovery, format (not wipe) data, then reboot recovery. Then flash magisk and then dm-verity.

4) then, and this is where you need the engineering abl to work, so you have full fastboot, you need to follow the instructions here and flash blank vbmeta. If you don't do this part any changes (like OP folder) won't work.

good luck
Hi,

I just fix the driver issue and able to flash the vbmeta in fastboot mode. However, after i flash the original abl_a in QFIL, the v409n keep booting to the fastboot mode instead of booting to android.

Is there anything I should do to make the phone boot to andorid again?

With the original abl_a, i can enter to download mode.
Should i re-flash the phone to latest firmware 30f or 20n and try the whole process again .


Thanks a lot!
 
Last edited:

AsItLies

Senior Member
Nov 4, 2009
981
426
tucson
Hi,

I just fix the driver issue and able to flash the vbmeta in fastboot mode. However, after i flash the original abl_a in QFIL, the v409n keep booting to the fastboot mode instead of booting to android.

Is there anything I should do to make the phone boot to andorid again?

With the original abl_a, i can enter to download mode.
Should i re-flash the phone to latest firmware 30f or 20n and try the whole process again .


Thanks a lot!
You have the abla and the laf a mixed up. The laf a controls download mode. Abl is for booting the device. Also, you are possibly on the wrong slot. Check which is active. Cheers
 

AsItLies

Senior Member
Nov 4, 2009
981
426
tucson
Hi,

I just fix the driver issue and able to flash the vbmeta in fastboot mode. However, after i flash the original abl_a in QFIL, the v409n keep booting to the fastboot mode instead of booting to android.

Is there anything I should do to make the phone boot to andorid again?

With the original abl_a, i can enter to download mode.
Should i re-flash the phone to latest firmware 30f or 20n and try the whole process again .


Thanks a lot!

if you are able to get to fastboot, which you say you are, then try this:

fastboot getvar all

towards the bottom of that output you'll see 'active slot', that will tell you which slot is booting currently. Try the fastboot command to change slots:

fastboot --set-active=(a or b - which ever one is not current)

then do 'fastboot reboot'.

It *sounds* like you're on the wrong slot, because if the eng_abl is flashed to the abl slot, it won't boot, only go straight to fastboot.

cheers
 

hkguy80

Member
Oct 31, 2012
22
2
if you are able to get to fastboot, which you say you are, then try this:

fastboot getvar all

towards the bottom of that output you'll see 'active slot', that will tell you which slot is booting currently. Try the fastboot command to change slots:

fastboot --set-active=(a or b - which ever one is not current)

then do 'fastboot reboot'.

It *sounds* like you're on the wrong slot, because if the eng_abl is flashed to the abl slot, it won't boot, only go straight to fastboot.

cheers
Hi,

I try to install the TWRP before I flash the blank vbmeta. After I flash the v35 eng to abl_a, I can enter to fastboot.
Then, I use the following command to flash the twrp to boot_a
>fastboot flash boot_a boot-twrp-30f_a.img
Then, I Enter TWRP recovery from fastboot directly.
I can enter the Twrp and format the data.

However, after I reboot to android, I won't able to enter the TWRP again.
I only can enter the original "Factory Data Reset". Is there any steps I missed?

Do I need to do the following tasks to enable the TWRP permanently?
  1. Copy TWRP-judypn-boot.img to the phone
  2. After I format the data in TWRP.
  3. Go to Advanced -> Install Recovery Ramdisk
  4. Select the TWRP image which you copied to your phone/sdcard earlier
I did not do the above steps before.
Is this the reason why I only can enter TWRP one time?

Thanks!!!
 
Last edited:

AsItLies

Senior Member
Nov 4, 2009
981
426
tucson
Hi,

I try to install the TWRP before I flash the blank vbmeta. After I flash the v35 eng to abl_a, I can enter to fastboot.
Then, I use the following command to flash the twrp to boot_a
>fastboot flash boot_a boot-twrp-30f_a.img
Then, I Enter TWRP recovery from fastboot directly.
I can enter the Twrp and format the data.

However, after I reboot to android, I won't able to enter the TWRP again.
I only can enter the original "Factory Data Reset". Is there any steps I missed?

Do I need to do the following tasks to enable the TWRP permanently?
  1. Copy TWRP-judypn-boot.img to the phone
  2. After I format the data in TWRP.
  3. Go to Advanced -> Install Recovery Ramdisk
  4. Select the TWRP image which you copied to your phone/sdcard earlier
I did not do the above steps before.
Is this the reason why I only can enter TWRP one time?

Thanks!!!

It sounds like twrp is installed, but maybe the 'factory data reset' screen is confusing you. When you see the 'factory data reset', you select yes, as though you were going to reset it, but instead of resetting, it will take you to twrp. (aslo do the vbmeta while you have fastboot still on though).

keep in mind, the v35eng abl has to be replaced with the original abl, for the device to boot, on that slot. I'm assuming you're doing this.

also, after formatting data and rebooting recovery, flash magisk and dm_verity. Then you should be all set.

cheers
 

hkguy80

Member
Oct 31, 2012
22
2
It sounds like twrp is installed, but maybe the 'factory data reset' screen is confusing you. When you see the 'factory data reset', you select yes, as though you were going to reset it, but instead of resetting, it will take you to twrp. (aslo do the vbmeta while you have fastboot still on though).

keep in mind, the v35eng abl has to be replaced with the original abl, for the device to boot, on that slot. I'm assuming you're doing this.

also, after formatting data and rebooting recovery, flash magisk and dm_verity. Then you should be all set.

cheers
I finally able to flash the magisk, dm_verity and vbmeta to the phone..


Thanks a lot for your help!!!
 
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    good. Yes the best way, especially with korean rom, is to flash the v35 eng abl to your not active slot, which I think in your case is 'b', so abl_b.

    the key to that working is you need to have twrp installed, so you can use it to set 'b' partition as active, then select 'reboot bootloader' and it will boot to fastboot. You can then use fastboot and follow the info in this vbmeta link. Read the directions.

    the other option (if u don't have twrp yet), would be to flash v35 eng to a, boot to fastboot, do the vbmeta stuff, then use fastboot to flash the original abl_a back, so it will boot.
    Either way, I will backup the original abl_a and abl_b before flashing. It is really scary to brick a phone.

    Thanks for your help again!!!!
    1
    It sounds like twrp is installed, but maybe the 'factory data reset' screen is confusing you. When you see the 'factory data reset', you select yes, as though you were going to reset it, but instead of resetting, it will take you to twrp. (aslo do the vbmeta while you have fastboot still on though).

    keep in mind, the v35eng abl has to be replaced with the original abl, for the device to boot, on that slot. I'm assuming you're doing this.

    also, after formatting data and rebooting recovery, flash magisk and dm_verity. Then you should be all set.

    cheers
    I finally able to flash the magisk, dm_verity and vbmeta to the phone..


    Thanks a lot for your help!!!
  • 1
    good. Yes the best way, especially with korean rom, is to flash the v35 eng abl to your not active slot, which I think in your case is 'b', so abl_b.

    the key to that working is you need to have twrp installed, so you can use it to set 'b' partition as active, then select 'reboot bootloader' and it will boot to fastboot. You can then use fastboot and follow the info in this vbmeta link. Read the directions.

    the other option (if u don't have twrp yet), would be to flash v35 eng to a, boot to fastboot, do the vbmeta stuff, then use fastboot to flash the original abl_a back, so it will boot.
    Either way, I will backup the original abl_a and abl_b before flashing. It is really scary to brick a phone.

    Thanks for your help again!!!!
    1
    It sounds like twrp is installed, but maybe the 'factory data reset' screen is confusing you. When you see the 'factory data reset', you select yes, as though you were going to reset it, but instead of resetting, it will take you to twrp. (aslo do the vbmeta while you have fastboot still on though).

    keep in mind, the v35eng abl has to be replaced with the original abl, for the device to boot, on that slot. I'm assuming you're doing this.

    also, after formatting data and rebooting recovery, flash magisk and dm_verity. Then you should be all set.

    cheers
    I finally able to flash the magisk, dm_verity and vbmeta to the phone..


    Thanks a lot for your help!!!
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