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[Guide] How to flash stock firmware and re-lock bootloader.

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By camy25695, Junior Member on 25th July 2018, 04:03 AM
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Guide: Returning to stock firmware + re-lock bootloader.

NOTE: following this guide will factory reset your phone so back up your data before hand.

Hi all, after having to do a fair bit of digging around last night in order to return my G7 to stock firmware i
figured i would make a all in one guide to make it a bit easier for people to follow!

First half of this guide is how to re-flash stock firmware:

1. Download LGUP here:Link
1.1 Download additional file we will need later: Link
1.2 Download stock KDZ file: Link
2. Install LGUP, after it has been installed extract the file from step 1.2 and place it here:
"C:\Program Files (x86)\LG Electronics\LGUP\model\common"
You will most likely have to create the common folder first and then place the file "LGUP_Common.dll" inside, this allows the LGUP software to recognise the device.

3. Next power down your device, once it is fully powered off hold the volume up key and insert the USB cable into your device
while continuing to hold volume up, continue to hold until your device enters download mode.

4. Open the LGUP software and drag the KDZ file into the file path section within the software, if your device is not showing
it means you dont have the correct drivers installed or haven't placed the .dll file from step 2 in the correct place.

5. Once the KDZ file is showing in LGUP simply click start and wait for the stock firmware to flash! Once it has completed
your device will reboot!

6. (Optional) download and install LG Bridge and check for any software updates after the flash has completed, OTA updates
can also be checked but in my experience it didnt show any updates where as LG Bridge did.

Second half of this guide will be how to re-lock the bootloader:

1. Download and install Android ADB + Fastboot drivers. The best guide I've found for this can be seen here:Link

2.Navigate to the folder where you have ADB and fastboot installed, usually this folder will be called platform tools.
hold shift and right click inside the folder then select "open powershell window here". Next make sure USB debugging is
enabled in developer settings and then head back to your powershell window and enter the following commands in order:
"adb reboot bootloader"
"fastboot oem lock"
"fastboot reboot"

3. Your phone will reboot and go through the usual first time start up, make sure to enable developer options again and
un-checking "OEM unlock". Your bootloader is now locked again!

If you followed the above steps you should now be back to complete stock! Enjoy
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25th July 2018, 10:16 AM |#2  
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I think it's better to flash stock firmware first to avoid problems when relocking the bootloader, because locking the bootloader just erases /data and /cache, and if you have some modifications like root or twrp it could cause a bootloop.
What I do is first flash stock and then relock the bootloader, with that order you will prevent any problems after relocking.
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25th July 2018, 12:31 PM |#3  
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Originally Posted by mprovi_15

I think it's better to flash stock firmware first to avoid problems when relocking the bootloader, because locking the bootloader just erases /data and /cache, and if you have some modifications like root or twrp it could cause a bootloop.
What I do is first flash stock and then relock the bootloader, with that order you will prevent any problems after relocking.

Thanks for the advice mate, I've updated the post and switched the order
26th July 2018, 04:18 PM |#4  
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Can you use this guide to flash different carrier firmware on device?
27th July 2018, 04:14 AM |#5  
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Originally Posted by mrpickem

Can you use this guide to flash different carrier firmware on device?

You can always try! I would probably recommend sticking to the firmware from your carrier though just to be on the safe side. If worst comes to worst you can always use this guide again to re-flash your carrier specific firmware if you find you are having issues! Let me know how you get on if you do try or need any help
28th July 2018, 03:13 AM |#6  
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Originally Posted by camy25695

You can always try! I would probably recommend sticking to the firmware from your carrier though just to be on the safe side. If worst comes to worst you can always use this guide again to re-flash your carrier specific firmware if you find you are having issues! Let me know how you get on if you do try or need any help

Thanks

I have been reading a bit and apparently there are different modems used between carriers. I currently have an unlocked Tmobile device and was wanting to flash the unlocked firmware...just dont want to risk bricking the phone. The phone works ok with tmobile fw, just wanted to get rid of bloat since I am now using it on ATT prepaid. Can find no info where anyone has done this. I 've flashed several Galaxy phones (to diff f/w)recently and Moto G's a few years back and it worked great.
28th July 2018, 11:33 AM |#7  
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Originally Posted by mrpickem

Thanks

I have been reading a bit and apparently there are different modems used between carriers. I currently have an unlocked Tmobile device and was wanting to flash the unlocked firmware...just dont want to risk bricking the phone. The phone works ok with tmobile fw, just wanted to get rid of bloat since I am now using it on ATT prepaid. Can find no info where anyone has done this. I 've flashed several Galaxy phones (to diff f/w)recently and Moto G's a few years back and it worked great.

I know it's possible to flash the boot.img seperate, as I've done that already myself but I'm unsure about flashing a different modem. I imagine the process will be very similar to flashing the boot but I'd need to do some digging and find out exactly! Even if you could there's no guarantee that it would work. I'll do some digging and see what I can find and get back to you!
28th July 2018, 05:34 PM |#8  
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Quote:
Originally Posted by mrpickem

I have been reading a bit and apparently there are different modems used between carriers. I currently have an unlocked Tmobile device and was wanting to flash the unlocked firmware...just dont want to risk bricking the phone.

The phone works ok with tmobile fw, just wanted to get rid of bloat since I am now using it on ATT prepaid. Can find no info where anyone has done this. I 've flashed several Galaxy phones (to diff f/w)recently and Moto G's a few years back and it worked great.

Assuming LG has made the same decisions for the G7 as they did for the V30, the answer is no.

At least on the V30 series, T-mobile variant can NOT be flashed to anything else because it has different RSA encryption keys from any other V30 phone. This is why back in May when we found the wonderful LG Oreo bootloader unlock exploit, every V30/V30+/V30S on the planet can now be bootloader unlocked and rooted -- EXCEPT for the the T-mobile H932. Because you need Oreo and you need (at least temporarily) fastboot flash commands.

So, all the carrier unlocked US998, European H930 and even the dual SIM H930DS (which have fastboot flash commands) can immediately be bootloader unlocked and rooted. For the others -- like the North American variants AT&T H931, Canadian H933, Verizon VS996, Sprint LS998 -- you first flash the carrier unlocked US998 firmware (aka Frankenstein) over those models to "convert" them to US998 to add back fastboot flash commands. We use dev patched LGUP. Then, after bootloader unlock and root, Sprint and Verizon users often flash back either all or part of their firmware to get back features or LTE bands (Sprint especially). They are still rooted, they still have TWRP. As a result of this, we suddenly now have tons of ROMs and custom kernels are under development.

But T-mobile H932 users are locked out of this development bonanza, because you can't cross flash anything without bricking the phone. I would assume the same for G7? T-mobile must have demanded this, because all the other North American V30 variants share the same RSA encryption keys which make cross flashing possible. If T-mobile demanded it for their V30, seems they would do the same for the next phone also.

Someone with a G7 came in to the V30 Frankenstein thread to ask if it works on G7, but that seems like something that should be discussed in this forum.
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29th July 2018, 01:16 AM |#9  
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Originally Posted by ChazzMatt

Assuming LG has made the same decisions for the G7 as they did for the V30, the answer is no.

At least on the V30 series, T-mobile variant can NOT be flashed to anything else because it has different RSA encryption keys from any other V30 phone. This is why back in May when we found the wonderful LG Oreo bootloader unlock exploit, every V30/V30+/V30S on the planet can now be bootloader unlocked and rooted -- EXCEPT for the the T-mobile H932. Because you need Oreo and you need (at least temporarily) fastboot flash commands.

So, all the carrier unlocked US998, European H930 and even the dual SIM H930DS (which have fastboot flash commands) can immediately be bootloader unlocked and rooted. For the others -- like the North American variants AT&T H931, Canadian H933, Verizon VS996, Sprint LS998 -- you first flash the carrier unlocked US998 firmware (aka Frankenstein) over those models to "convert" them to US998 to add back fastboot flash commands. We use dev patched LGUP. Then, after bootloader unlock and root, Sprint and Verizon users often flash back either all or part of their firmware to get back features or LTE bands (Sprint especially). They are still rooted, they still have TWRP. As a result of this, we suddenly now have tons of ROMs and custom kernels are under development.

But T-mobile H932 users are locked out of this development bonanza, because you can't cross flash anything without bricking the phone. I would assume the same for G7? T-mobile must have demanded this, because all the other North American V30 variants share the same RSA encryption keys which make cross flashing possible. If T-mobile demanded it for their V30, seems they would do the same for the next phone also.

Someone with a G7 came in to the V30 Frankenstein thread to ask if it works on G7, but that seems like something that should be discussed in this forum.


Thanks for the reply and that's kinda what what I been reading, just not as much detail. Thanks for detailed explanation
31st July 2018, 07:19 PM |#10  
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Originally Posted by ChazzMatt

Assuming LG has made the same decisions for the G7 as they did for the V30, the answer is no.

At least on the V30 series, T-mobile variant can NOT be flashed to anything else because it has different RSA encryption keys from any other V30 phone. This is why back in May when we found the wonderful LG Oreo bootloader unlock exploit, every V30/V30+/V30S on the planet can now be bootloader unlocked and rooted -- EXCEPT for the the T-mobile H932. Because you need Oreo and you need (at least temporarily) fastboot flash commands.

So, all the carrier unlocked US998, European H930 and even the dual SIM H930DS (which have fastboot flash commands) can immediately be bootloader unlocked and rooted. For the others -- like the North American variants AT&T H931, Canadian H933, Verizon VS996, Sprint LS998 -- you first flash the carrier unlocked US998 firmware (aka Frankenstein) over those models to "convert" them to US998 to add back fastboot flash commands. We use dev patched LGUP. Then, after bootloader unlock and root, Sprint and Verizon users often flash back either all or part of their firmware to get back features or LTE bands (Sprint especially). They are still rooted, they still have TWRP. As a result of this, we suddenly now have tons of ROMs and custom kernels are under development.

But T-mobile H932 users are locked out of this development bonanza, because you can't cross flash anything without bricking the phone. I would assume the same for G7? T-mobile must have demanded this, because all the other North American V30 variants share the same RSA encryption keys which make cross flashing possible. If T-mobile demanded it for their V30, seems they would do the same for the next phone also.

Someone with a G7 came in to the V30 Frankenstein thread to ask if it works on G7, but that seems like something that should be discussed in this forum.

Ok what about flashing the European LMG710EM firmware onto the Sprint G7? Would i risk bricking my device? Im trying to find a solution to unlocking my sprint phone
4th August 2018, 12:09 AM |#11  
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Originally Posted by mastervideogamer79

Ok what about flashing the European LMG710EM firmware onto the Sprint G7? Would i risk bricking my device? Im trying to find a solution to unlocking my sprint phone

did you try flashing G710EM firmware in the sprint g7? i also have a sprint variant and want to unlock it.

UPDATE: just tried to flash it but lg up doesnt even start flashing the kdz file, it gives "LAF WRITE PROTECTION" and "Cross flash is not supported" messages

luckily phone is working just fine with the original software, i mean it didnt bricked the phone since it didnt even started to flash.

in other post i saw a user that tried flashing tmobile firmware with lg v20 dll and bricked his sprint g7
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