Hi,
I purchased the phone in the UK from the network carrier Vodafone. I have done a fair bit of research on the rooting and unrooting process mainly via videos and reading tutorials on XDA.
I would like to root the phone and gain super user access and install some Xposed modules but would also like to be able to unroot and flash back to a stock Vodafone firmware encase I need to claim under warranty. I have been trolling the internet to get the correct KDZ file and found this site (ttp://devtester.ro/projects/lg-firmwares/country.php?country=United+Kingdom). I believe that the correct firmware may be on here but am a little confused on what the suffix and software version means to be honest.
The reason for my confusion is that I updated the firmware to 6.0 Marshmallow through the LG bridge but when I now check my phones software version it states v20b-234-15. I assume this is right but from memory the first software version when I got the phone was something like H81510B_00.
I cant remember exactly what it was before unfortunately but the KDZ files I have found state H81510C_00 (Suffix - AVDFVK) and H81510C_00 (AVDFLR) and this does seem to make sense but I'm thinking it was B instead of C but and not 100% on that.
Do you think these KDZ files would be the correct one to flash back to encase I run in to some problems rooting?
I am also assuming that this KDZ is Android Lollipop and not Marshmallow so is it OK to use this to revert back from Marshmallow?
Thanks and any help would be much appreciated.
Ross
The 10X version are all Lollipop, 20X is marshmallow.
When flashing a KDZ on your phone, what's important is what model your phone is. H815 in your case.
If you want to restore to stock in case something goes wrong, you can find everything here: http://forum.xda-developers.com/g4/general/guide-lg-g4-stock-firmware-to-stock-kdz-t3107848
In there is a link to this directory: http://storagecow.eu/index.php?dir=Xda/LG+G4/ where you find pretty much all KDZ files for G4 phones.
I'm not that experienced myself, but I rooted my phone just recently and I can share my experience with you.
I have a H815. It was a V10c-TWN-XX version (Taiwan). I updated to Marshmallow with LG Bridge also and the new software version was V20b-TWN-XX.
Marshmallow rooting is not possible on my phone because I can't unlock the bootloader on it. And Marshmallow rooting is only possible with an unlocked bootloader. Unlocking the bootloader is only possible on European phones (http://developer.lge.com/resource/mobile/RetrieveBootloader.dev?categoryTypeCode=ANRS). I asked autoprime (renown user and developer here) if I can unlock bootloader after flashing an European KDZ on it. He said no, having European software on it is not enough, it has to be a phone manufactured for the european market. Dont know why, guess because of different hardware.
So, not being able to root MM, I had to revert back to stock (downgrade) using one of the KDZs.
I chose the most recent one in the directory I linked (which is the Poland H81510E). In the "Go Back to Stock" thread I linked the OP says to use LG Flash Tool 2014, which unfortunately doesn't work with Marshmallow. But fret not, it works with LG UP! http://forum.xda-developers.com/g4/help/lgup-install-kdz-mm-lp-t3249803
When I tried flashing the KDZ with Flash Tool 2014, the process failed with an error at 5%. It worked flawlessly with LG UP. Here's more information regarding downgrading, but it really isnt hard. Just download + install LG UP. Launch it. Connect your phone. Choose KDZ file. Select option "upgrade". Hit start.
NOTE: after the firmware update was done, the phone rebooted automatically and for me it stuck at at the LG Logo (bootloop). But a simple hard factory reset did it, the phone booted and my new version was 10e-something. With Lollipop 5.1 of course.
After that, I rooted my phone using this pre-rooted image: http://forum.xda-developers.com/g4/development/h815-eu-l-p-t-sea-twn-t3176195
and this guide: http://forum.xda-developers.com/g4/...-tmo-vzw-intl-variants-soon-root-lg-t3164765/
I now have a "H81510e-EUR-XX" Lollipop 5.1 with root (SuperSU 2.49).
I don't really know about Vodafone and if carrier specific firmware is necessary in this case. If not, you could use any 815 firmware.
From the site you have linked with the KDZ files..... it seems they are all the same.
If you check the table for H815 KDZs from Vodafone, there are some 10C and 10D versions. Now I compared the fileKey parameter in the URL to the 10C files and the 10D files and also the bytes of the files.
All the 10C version are identical to each other, same for 10D.
Check out this screenshot I made for you: http://i.imgur.com/Ie0w4us.png
Bytes are also identical, so it's pretty safe to say those are the same files.
Dont know why they are listed several times there. The suffix doesnt matter.
I'd grab a 10D if I were you. But I think the Poland 10E should work, too. Better confirm it with somebody else though.
If you flash your system to 10e, you can use the pre-rooted image I used. Otherwise you will have to inject root yourself: http://forum.xda-developers.com/g4/general/lg-g4-100-root-success-directives-root-t3180586. In this method you create an image of your system and inject root into the image, which you then flash back on your phone.
I'm trying to downgrade my G4 from marshmallow back to lollipop. My anti-rollback # is 2, and according to this as long as the anti-rollback # is the same on both the installed version and the kdz, flashing the downgrade doesn't hard brick the device.
So far I've been unable to either find one, or clarify if one exists for my variant or not. Can anyone help? Thanks.
In any event ...
2PiSquared said:
I'm trying to downgrade my G4 from marshmallow back to lollipop. My anti-rollback # is 2, and according to this as long as the anti-rollback # is the same on both the installed version and the kdz, flashing the downgrade doesn't hard brick the device.
So far I've been unable to either find one, or clarify if one exists for my variant or not. Can anyone help? Thanks.
Click to expand...
Click to collapse
In any event ... if you do happen to find an LP stock image to try, make sure you use LGUP-NEW (https://forum.xda-developers.com/g4/help/lgup-install-kdz-mm-lp-t3249803) to downgrade to the stock Lollipop image as it should throw throw up an error regarding the anti-rollback version roll back and not proceed with the rollback, thereby avoiding any brick worries for you ...
You may have to do a bit of trial and error but it would help if you post your exact software version that you are on now for anyone to assist you in at least pointing you in the right direction for LP kdz's to try.
sdembiske said:
In any event ... if you do happen to find an LP stock image to try, make sure you use LGUP-NEW (https://forum.xda-developers.com/g4/help/lgup-install-kdz-mm-lp-t3249803) to downgrade to the stock Lollipop image as it should throw throw up an error regarding the anti-rollback version roll back and not proceed with the rollback, thereby avoiding any brick worries for you ...
You may have to do a bit of trial and error but it would help if you post your exact software version that you are on now for anyone to assist you in at least pointing you in the right direction for LP kdz's to try.
Click to expand...
Click to collapse
Oh, so LGUP-NEW pretty much let's you throw any kdz at the device and if it would have normally bricked the device, instead it comes up with an error? That's pretty neat.
My specific software version US99125a, and if it helps at all, my end goal is to hopefully root my device.
Well, not any old kdz ...
2PiSquared said:
Oh, so LGUP-NEW pretty much let's you throw any kdz at the device and if it would have normally bricked the device, instead it comes up with an error? That's pretty neat.
My specific software version US99125a, and if it helps at all, my end goal is to hopefully root my device.
Click to expand...
Click to collapse
Well, not any old kdz ... You want to keep to US Cellular versions. This site lists a couple of LP kdz's:
https://boycracked.com/2016/10/14/official-lg-g4-us991-us-cellular-stock-rom/
I suggest you check out: [Discussion] US Cellular us991 at https://forum.xda-developers.com/g4/general/cellular-us991-t3151051
read the posts and then post any questions you might have there and google XDA - LG G4 US991 for additional input.
That's all I got for you ...
2PiSquared said:
I'm trying to downgrade my G4 from marshmallow back to lollipop. My anti-rollback # is 2, and according to this as long as the anti-rollback # is the same on both the installed version and the kdz, flashing the downgrade doesn't hard brick the device.
So far I've been unable to either find one, or clarify if one exists for my variant or not. Can anyone help? Thanks.
Click to expand...
Click to collapse
Hey, don't want to revive an older thread but, were you successful in downgrading? My anti rollback is at #2 as well..
has anyone been able to downgrade? i got #2 rollback and can't get over it
My device is an H812. I got nougat by modifying an F500L KDZ in a hex editor and replacing 'F500L' with 'H812' and flashing in LGUP. The modem didn't work, so I decided to downgrade.
Courtesy of @da.vandenham who created a thread for downgrading from this modified nougat software, I downloaded the KDZ he provided and flashed it in LGUP.
After this, I attempted flashing stock for my device, though LGUP said that the KDZ is invalid.
My device is currently in a state where there the screen will not turn on but is clearly in the setup menu. LGUP now detects it as an H815.
Any help getting out of this would be very much appreciated! I really need this phone to work for school!
The following are versions of KDZs I tried flashing:
H81220u
H81220z
F500L30b (this is one I modified for my H812)
H81520o (KDZ provided by @da.vandenham)
F500K30C (I also modified this)
Here is the thread I mentioned (see OP):
https://forum.xda-developers.com/g4/general/f500-downgrade-nougat-to-mm-t3650310/page3
Can you flash the newest global unofficial zip?
fegitoli said:
My device is an H812. I got nougat by modifying an F500L KDZ in a hex editor and replacing 'F500L' with 'H812' and flashing in LGUP. The modem didn't work, so I decided to downgrade.
Courtesy of @da.vandenham who created a thread for downgrading from this modified nougat software, I downloaded the KDZ he provided and flashed it in LGUP.
After this, I attempted flashing stock for my device, though LGUP said that the KDZ is invalid.
My device is currently in a state where there the screen will not turn on but is clearly in the setup menu. LGUP now detects it as an H815.
Any help getting out of this would be very much appreciated! I really need this phone to work for school!
The following are versions of KDZs I tried flashing:
H81220u
H81220z
F500L30b (this is one I modified for my H812)
H81520o (KDZ provided by @da.vandenham)
F500K30C (I also modified this)
Here is the thread I mentioned (see OP):
https://forum.xda-developers.com/g4/general/f500-downgrade-nougat-to-mm-t3650310/page3
Click to expand...
Click to collapse
I would suggest first you post to the thread where you got the H815 kdz from: https://forum.xda-developers.com/g4/general/f500-downgrade-nougat-to-mm-t3650310 as well as: https://forum.xda-developers.com/g4/development/kdz-7-0-nougat-lg-g4-f500s-l-k-t3638530
2nd (and probably the best for getting a knowledgeable & helpful answer), post your issue to steadfasterX's thread at: https://forum.xda-developers.com/g4/general/bl-unlock-unlock-bootloader-proof-t3648288
I suspect it has to do with the 815 bootloader ...
For future reference, modem issues can sometimes be solved by erasing modemst1 and modemst2 ...
harysviewty said:
Can you flash the newest global unofficial zip?
Click to expand...
Click to collapse
I can't flash any zips because my phone can't be BL unlocked.
Sent from my LG-H873 using XDA Labs
Guide: How to upgrade/downgrade/restore OFFICIAL firmware on your V30.
Requirements:
LG V30
Windows PC
Official Firmware file for your V30 ending with .kdz. You can find it here https://forum.xda-developers.com/lg-v30/development or here https://lg-firmwares.com/
Bootloader does not need to be unlocked. All variants can be flashed using this method.
Only fully official, LG signed and blessed, unmodified firmware can be flashed using this method. No custom roms or recoveries!
Lets go:
Download and install LG USB drivers from here.
Download and install LG UP 1.14.3 from here.
Download .dll file for our V30, attached at the bottom of this post.
Navigate to C:\Program Files (x86)\LG Electronics\LGUP\model
Create folder called "common" and unzip the .dll file inside of it.
Connect the phone to your PC
[Optional]Open Device Manager and verify if under Ports you can see LGE Mobile USB Serial Port (COM...) to make sure the LG driver was installed correctly and the phone is visible.
Launch LGUP.exe
Select process called "UPGRADE" Warning: Selecting Refurbish will wipe user data.
Select the firmware file.
Click Start!
Your phone will automatically reboot into Download mode and upgrade firmware.
There's no need to do a factory reset afterwards but you can if you encounter any issues ofc. (I haven't)
Thanks for the guide.
thank you. I would love to try the MIUI ROM on this device.
padmanek said:
Requirements:
LG V30
Windows PC
Official Firmware file for your V30 ending with .kdz. You can find it here https://forum.xda-developers.com/lg-v30/development or here https://lg-firmwares.com/
Bootloader does not need to be unlocked. All variants can be flashed using this method.
Lets go:
Download and install LG USB drivers from here.
Download and install LG UP 1.14.3 from here.
Download .dll file for our V30, attached at the bottom of this post.
Navigate to C:\Program Files (x86)\LG Electronics\LGUP\model
Create folder called "common" and unzip the .dll file inside of it.
Connect the phone to your PC
[Optional]Open Device Manager and verify if under Ports you can see LGE Mobile USB Serial Port (COM...) to make sure the LG driver was installed correctly and the phone is visible.
Launch LGUP.exe
Select process called "UPGRADE" Warning: Selecting Refurbish will wipe user data.
Select the firmware file.
Click Start!
Your phone will automatically reboot into Download mode and upgrade firmware.
There's no need to do a factory reset afterwards but you can if you encounter any issues ofc. (I haven't)
Click to expand...
Click to collapse
My apologies if I misunderstood. Is this a way to apply alternative ROMs even on models with locked bootloaders and the ADB Commands stripped out such as the H 933? I know you said already that it will work on any variant but I had lost hope that this model would ever allow modding of the rum. I just want to make sure I'm not misunderstanding the intention of your guide.
Sent from my LG-H933 using Tapatalk
Mad Medik said:
My apologies if I misunderstood. Is this a way to apply alternative ROMs even on models with locked bootloaders and the ADB Commands stripped out such as the H 933? I know you said already that it will work on any variant but I had lost hope that this model would ever allow modding of the rum. I just want to make sure I'm not misunderstanding the intention of your guide.
Click to expand...
Click to collapse
It clearly says in the title of the thread and in the requirements that you can only flash full official (stock) firmware using this method...
Nothing custom. Everything needs to be RSA signed by LG.
astikv said:
thank you. I would love to try the MIUI ROM on this device.
Click to expand...
Click to collapse
Like above, only official (stock), LG signed and blessed firmware can be flashed using this method.
padmanek said:
It clearly says in the title of the thread and in the requirements that you can only flash full official (stock) firmware using this method...
Nothing custom. Everything needs to be RSA signed by LG.
Like above, only official (stock), LG signed and blessed firmware can be flashed using this method.
Click to expand...
Click to collapse
Oh well, wishful thinking amd my mistake. I read it as upgrade or downgrade (eg various images) or restore stock.
Sent from my LG-H933 using Tapatalk
padmanek said:
It clearly says in the title of the thread and in the requirements that you can only flash full official (stock) firmware using this method...
Nothing custom. Everything needs to be RSA signed by LG.
Like above, only official (stock), LG signed and blessed firmware can be flashed using this method.
Click to expand...
Click to collapse
I meant in 1 future.
padmanek said:
Requirements:
LG V30
Windows PC
Official Firmware file for your V30 ending with .kdz. You can find it here https://forum.xda-developers.com/lg-v30/development or here https://lg-firmwares.com/
Bootloader does not need to be unlocked. All variants can be flashed using this method.
Only fully official, LG signed and blessed, unmodified firmware can be flashed using this method. No custom roms or recoveries!
Lets go:
Download and install LG USB drivers from here.
Download and install LG UP 1.14.3 from here.
Download .dll file for our V30, attached at the bottom of this post.
Navigate to C:\Program Files (x86)\LG Electronics\LGUP\model
Create folder called "common" and unzip the .dll file inside of it.
Connect the phone to your PC
[Optional]Open Device Manager and verify if under Ports you can see LGE Mobile USB Serial Port (COM...) to make sure the LG driver was installed correctly and the phone is visible.
Launch LGUP.exe
Select process called "UPGRADE" Warning: Selecting Refurbish will wipe user data.
Select the firmware file.
Click Start!
Your phone will automatically reboot into Download mode and upgrade firmware.
There's no need to do a factory reset afterwards but you can if you encounter any issues ofc. (I haven't)
Click to expand...
Click to collapse
Out of interest, will this work on a rooted V30. I seem to struggle to get LGUP to boot my phone into download mode. Is it because I have twrp as recovery?
Sent from my LG-H930 using Tapatalk
thenoble06 said:
Out of interest, will this work on a rooted V30. I seem to struggle to get LGUP to boot my phone into download mode. Is it because I have twrp as recovery?
Sent from my LG-H930 using Tapatalk
Click to expand...
Click to collapse
It will work as long as your /laf partition is in tact. It containts the DL mode. It has nothing to do with /recovery partition where you most likely flashed TWRP.
Read this: https://forum.xda-developers.com/v20/how-to/laf-download-mode-how-root-t3676011
Just so I don't brick my device, I have an H930DS, therefore any firmware marked for this model (https://lg-firmwares.com/lg-h930ds-firmwares/), regardless of region, would work on my phone? My phone is currently on HK region version, can I flash the Indian firmware for the same model?
sasc said:
Just so I don't brick my device, I have an H930DS, therefore any firmware marked for this model (https://lg-firmwares.com/lg-h930ds-firmwares/), regardless of region, would work on my phone? My phone is currently on HK region version, can I flash the Indian firmware for the same model?
Click to expand...
Click to collapse
Probably not but feel free to try it and let us know how that goes.
sasc said:
Just so I don't brick my device, I have an H930DS, therefore any firmware marked for this model (https://lg-firmwares.com/lg-h930ds-firmwares/), regardless of region, would work on my phone? My phone is currently on HK region version, can I flash the Indian firmware for the same model?
Click to expand...
Click to collapse
I have no idea about cross region firmware flashing. I have not found any official documentation about how each of LG UP's functions exactly works, it's all user experience here on XDA. Supposedly, every region has firmware signed with different RSA key which is verified upon trying to flash and it will reject you if it's a mismatch. Also I doubt Indian region has the same bands as HK so you might cripple your mobile signal if you happen to be on a band that is not supported in Indian firmware. Personally I don't recommend trying it but its up to you Please share your experience if you do
I know for sure that all H930 sold in EU, regardless of what carrier can be flashed with the same H930 unbranded EU firmware, which removes all carrier bloat and branding.
@sasc Check the RSA signature of your firmware and compare it to the firmware you want to flash. If they match, then it won't brick your phone. Your phone may not work, but at least your will have access to DL mode. If they don't match, you will definitely brick your phone..
-- Brian
padmanek said:
I have no idea about cross region firmware flashing. I have not found any official documentation about how each of LG UP's functions exactly works, it's all user experience here on XDA. Supposedly, every region has firmware signed with different RSA key which is verified upon trying to flash and it will reject you if it's a mismatch. Also I doubt Indian region has the same bands as HK so you might cripple your mobile signal if you happen to be on a band that is not supported in Indian firmware. Personally I don't recommend trying it but its up to you Please share your experience if you do
I know for sure that all H930 sold in EU, regardless of what carrier can be flashed with the same H930 unbranded EU firmware, which removes all carrier bloat and branding.
Click to expand...
Click to collapse
India and HK are both global GSM regions. The bands are the same, just like Europe.
runningnak3d said:
@sasc Check the RSA signature of your firmware and compare it to the firmware you want to flash. If they match, then it won't brick your phone. Your phone may not work, but at least your will have access to DL mode. If they don't match, you will definitely brick your phone..
-- Brian
Click to expand...
Click to collapse
Could you please tell us what's the best way to check the signatures?
Okay.. I bring good news! You can definitely flash any KDZ as long as the model number is exactly the same. I flashed the HK Reginal kdz on my H930DS from India and I now have working VoLTE and VoWiFi.
In short, get the CORRECT kdz of the desired region for your model number, use LGUP, Upgrade option, and let it do its thing. Simple. This keeps the device official and under warranty.
PS - Please backup all data before doing this. Even though it is just an upgrade, play it safe. Just in case!
spacebar2011 said:
Okay.. I bring good news! You can definitely flash any KDZ as long as the model number is exactly the same. I flashed the HK Reginal kdz on my H930DS from India and I now have working VoLTE and VoWiFi.
In short, get the CORRECT kdz of the desired region for your model number, use LGUP, Upgrade option, and let it do its thing. Simple. This keeps the device official and under warranty.
PS - Please backup all data before doing this. Even though it is just an upgrade, play it safe. Just in case!
Click to expand...
Click to collapse
Thats great news ?. One question - to get VoWifi working, person at the other end should also have VoWifi? Or we can call VoWifi to VoLte. I have never tried VoWifi so just curious to know.
manishvy said:
Thats great news . One question - to get VoWifi working, person at the other end should also have VoWifi? Or we can call VoWifi to VoLte. I have never tried VoWifi so just curious to know.
Click to expand...
Click to collapse
VoWiFi does not need the person at the other end to have any special call options.
spacebar2011 said:
Okay.. I bring good news! You can definitely flash any KDZ as long as the model number is exactly the same. I flashed the HK Reginal kdz on my H930DS from India and I now have working VoLTE and VoWiFi.
In short, get the CORRECT kdz of the desired region for your model number, use LGUP, Upgrade option, and let it do its thing. Simple. This keeps the device official and under warranty.
PS - Please backup all data before doing this. Even though it is just an upgrade, play it safe. Just in case!
Click to expand...
Click to collapse
Thanks amazing news! I will try this asap to get Volte on my HG 930DS (India carrier)
spacebar2011 said:
Okay.. I bring good news! You can definitely flash any KDZ as long as the model number is exactly the same. I flashed the HK Reginal kdz on my H930DS from India and I now have working VoLTE and VoWiFi.
In short, get the CORRECT kdz of the desired region for your model number, use LGUP, Upgrade option, and let it do its thing. Simple. This keeps the device official and under warranty.
PS - Please backup all data before doing this. Even though it is just an upgrade, play it safe. Just in case!
Click to expand...
Click to collapse
So...kind of didn't work.
I used the H930DS marked India in lgfirmwares. The flashing process went fine, except for the phone getting stuck right after the last restart and the screen went blank. Waited a couple of mins and forced a restart using the power button..booted fine but all data was gone. Thankfully i did backup some stuff, but not all..
Checked the Software version, it says V11i-GLOBAL-COM, which is obviously not the India version. And, I still dont have Volte!! So, this was futile..
Can anyone point me to a certified H930DS India KDZ?
Hello Dear Brothers,
I have tried so many ways to root my LG-G4 (LG-F500S) Korean Version . But every time i failed. Now I need help of a genius.
amit31928 said:
Hello Dear Brothers,
I have tried so many ways to root my LG-G4 (LG-F500S) Korean Version . But every time i failed. Now I need help of a genius.
Click to expand...
Click to collapse
There may be a possibility to not only root your phone but also to install some custom rom versions, e.g., LineageOS Oreo, Pie.
However, it is first dependent on a couple of things:
1). You must be on stock Marshmallow - if you are on Nougat firmware now and cannot rollback to Marshmallow, you are out of luck.
2). Your ARB (Anti-RollBack) version must be 2 or lower. If your ARB version is 3 or higher, you are out of luck.
Your first step is to ascertain your current ARB version (using SALT) as that will help determine if and what version of Marshmallow you can rollback to safely (rolling back using LGUP-New, ONLY for this particular step ) and whether you are then able to proceed to unlock your bootloader.
If you can meet these requirements, then proceed to free your phone following the directions in this thread: [UNLOCK][UNOFFICIAL][G4] Unlock **ANY** LG G4 device with UsU. Read everything thoroughly there IF you are able to proceed and make sure you understand it fully and follow it exactly
If and when you've unlocked your bootloader with steadfasterX's brilliant UsU method ... then and only then you can proceed to install TWRP (custom recovery), and Magisk, for example (for root) and install a custom rom to upgrade your system to the latest security patches, etc.
sdembiske said:
There may be a possibility to not only root your phone but also to install some custom rom versions, e.g., LineageOS Oreo, Pie.
However, it is first dependent on a couple of things:
1). You must be on stock Marshmallow - if you are on Nougat firmware now and cannot rollback to Marshmallow, you are out of luck.
2). Your ARB (Anti-RollBack) version must be 2 or lower. If your ARB version is 3 or higher, you are out of luck.
Your first step is to ascertain your current ARB version (using SALT) as that will help determine if and what version of Marshmallow you can rollback to safely (rolling back using LGUP-New, ONLY for this particular step ) and whether you are then able to proceed to unlock your bootloader.
If you can meet these requirements, then proceed to free your phone following the directions in this thread: [UNLOCK][UNOFFICIAL][G4] Unlock **ANY** LG G4 device with UsU. Read everything thoroughly there IF you are able to proceed and make sure you understand it fully and follow it exactly
If and when you've unlocked your bootloader with steadfasterX's brilliant UsU method ... then and only then you can proceed to install TWRP (custom recovery), and Magisk, for example (for root) and install a custom rom to upgrade your system to the latest security patches, etc.
Click to expand...
Click to collapse
Nought version..what should i do now
'"
amit31928 said:
Nought version..what should i do now
Click to expand...
Click to collapse
You missed a point: "... if you are on Nougat firmware now and cannot rollback to Marshmallow ..."
So, the question now is "Can you rollback to Marshmallow?"
To determine if you can, use SALT that I linked in my first post and determine your ARB version - if it is above 2, i.e., 3 or higher, the answer is no. If it is 2 or lower, then the answer is possibly. Next, if you do not have a backup copy of your original Marshmallow kdz (firmware), then you will have to download one for your model and region. You can check this link if that is the case: https://lg-firmwares.com/lg-f500s-firmwares/#tab=firmwares or google for a match. You will have to download a kdz from there or wherever else you find one and check the ARB version, extracting it in SALT. If the ARB version is the same (and 2 or lower) in both your Nougat and the Marshmallow kdz you extracted, then you should be good to go to rollback to Marshmallow and then proceed to unofficially unlock your phone. Note: If it is lower (on the Marshmallow kdz vs your current Nougat firmware), you will hard brick your phone (you can go to a higher ARB version BUT it cannot be higher than 2).