[Downgrade] LG G4 ZVI to ZVB LS991

[lokichaos]

just wanted to share my experience in downgrading my G4's software version and want to let everyone know it's possible.

using the guide by @tabp0le here: https://forum.xda-developers.com/sp...-mellowmallow-debloated-60fps-camera-t3358340

Depending on which current version you are on you will need the official TOT to get the process going. Once you pull your cable use the MellowMallow .img (ZVB) provided by tabp0le in his original guide and his diag commands.

I have successfully downgraded two ls991's to ZVB using this method. I do not know if this will work on other variations on the phone. THE KEY POINT IS THAT I AM VERY SURE THAT WHILE ON ZVI MY ARB WAS ON ARB 4 AND I WAS ABLE TO SUCCESSFULLY DOWNGRADE TO A LOWER software. Here's the thing, my ARB STAYED THE SAME so while ZVB is techincally ARB 2 my ARB stayed at 4.

with this in mind, you should, be able to downgrade to ZVA. I have not tested going from ZVI to ZVA so anyone willing to you will be trying the downgrade at your OWN RISK! I cannot assist you if you brick your phone but at this point I don't think too many people are worried about bricking the phone especially how cheap you can pick one up. the problem remains that you will still be on a higher ARB and the existing root methods were all done on a ARB <=2 .

quick guide (using tabp0le's original instructions):

0. if you haven't yet, read tabp0le's post, download all the files including LGUP and the official TOT for whatever version you are on (if you are on ZVI then download the ZVI.tot)

1. place the ZVB .img custom rom on tabp0le's post in your internal storage default folder. I will say the MellowMallow rom he provided is a a little buggy but the trade-off to be back pre security patch for 6.0 and unlocked sim card was worth it. make sure you use the right rom for your phone. If you have a global phone use the global rom/img. I haven't tested it yet but once you are back on ZVB you should be able to flash the official ZVB TOT so you can have a completely stock LG G4 with ZVB.

2. Place phone in diag mode by dialing ##DIAG# on dialer.

3. hook your phone into pc and change your usb mode to "charge only"

4. open up LGUP, if you have all your drivers installed from tabp0le's post then you should see your phone/version pop up.

5. select the TOT for your installed version on your phone, for me it was ZVI. hit start.

6. THIS IS WHERE YOU NEED ABSOLUTE ATTENTION TO DETAIL. Your phone will reboot. Keep an eye on the completion percent. 9% is the magic number. I would recommend watching your phone though. As soon as it says "COM XX" in green YOU PULL THE USB PLUG. if done right when it pops up, you would have pulled it right at 9%. if you are late, you risk bricking your device. However I will say that I did pull it at 11% before and all I did was replug the USB and allow the software version to update/reboot my phone. everything was fine and I attempted the whole process again successfully. if you just zone out and miss the sweet spot no worries, just allow the software to update and attempt the whole process again, DO NOT TRY TO STOP THE SOFTWARE UPDATE ONCE IT'S PAST 9%.

7. did you nail it at 9%? GREAT! continue on.

8. close down LGUP and open up a command prompt and navigate to the folder with "ports.bat" from tabp0le's post. run ports.bat. the instructions are word for word from tabp0le's post so I will just quote them.

* Now check which COM# for LGDIAG port
* Send_Command.exe \\.\COMxx
* Command to flash is listed next to the download near the end of this post.
* After you issue the command with Send_Command.exe, it should pause for about 2 minutes then go back to #.
* Type LEAVE then pull battery when complete.

here are the commands to flash based on version:
US ROM:

dd if=/data/media/0/MellowMallow_LS991ZVB_v1.04.img bs=8192 seek=65536 count=557312 of=/dev/block/mmcblk0

GLOBAL ROM:

dd if=/data/media/0/MellowMallow_LS991ZVB_v1.04_Global.img bs=8192 seek=65536 count=557312 of=/dev/block/mmcblk0

if done correctly the command will "process" for a minute, it will look like nothing is happening, but that's a good thing! wait for the # to re-appear after about 3 to 6 minutes. once it does type "LEAVE", unplug your phone and reboot.

VIOLA! you should be on ZVB! hope this helps give this underrated phone some new life for those out there who gave up on it.

to check your version, download Hidden Menu APK
open it up after install and select:
* SVC Menu --> Version Info

https://androidfilehost.com/?fid=745425885120746375

update next post below

 

[lokichaos]

follow up post:

Okay! good news. I went ahead and tested flashing another (custom) rom image using above method and everything went fine! I know there aren't a lot of G4 users out there left but hey, it's something..

*WARNING* Again, this is a highly untested process, your risk for brick is very high. Know that before you proceed *WARNING*

just download whatever rom you want and place it in your root internal storage folder.

when you get to

dd if=/data/media/0/"rom_name".img bs=8192 seek=65536 count=557312 of=/dev/block/mmcblk0

you will, instead, replace "rom_name" with the name of the (custom) rom you are trying to install. so, for instance, your rom name is "ZVAUltra" you will use:

dd if=/data/media/0/ZVAUltra.img bs=8192 seek=65536 count=557312 of=/dev/block/mmcblk0

for simplicity sake you can just rename the rom before you put it on your sd card to crom.img or something.
Right now, my LS991 is running UltraPOP AOSP created by @Agimax, his thread:
https://forum.xda-developers.com/sprint-g4/development/rom-mm-ultrapop-aospish-v1-0-t3351164

Bugs:
depending on the rom, you may have some buggy responses. I now have a constant "sd card is corrupt error" so your mileage will vary with this method. working on fixing this. I have NOT tested changing android versions ( android 6.0 to 5.0, etc...) so you will be DOING SO AT YOUR OWN RISK.

edit: more bugs. Once your apps start to update, dialer codes won't work properly (can't put phone in DIAG mode), bluetooth no longer works and you'll have some issues with SD showing up as corrupt. still researching. I might attempt a downgrade to ZV6 stock rom and root (I can dream, can't I?)to see how it goes. updates to come!

the only fix for the dialer code and the other issues is to format your phone either from "backup and reset" option in settings or through recovery mode. don't let your phone update! Put it in airplane mode or take out your SIM card. if you want to return to ZVI follow the steps outlined above with LGUP except this time just allow the update to finish and your phone will be on the latest software version.

 

[ardian1899]

I really surprised to see almost no response for this thread. The information provided here is awesome.

 

[lokichaos]

I really surprised to see almost no response for this thread. The information provided here is awesome.

hahah, thanks! I really didn't expect to get too much response here. Most people only care if I was claiming to have achieved root, which I haven't. I did manage to downgrade to ZV6, which is the "rootable" rom but the few attempts I made at rooting caused a soft-brick and I had to restore a TOT to remove the soft-brick.

A lot of this info here was done by piecing together info others provided on this site so I was passing it along in the hopes this info could help another take another step forward.

From all my messing with this method it is fairly safe, worst I've gotten on two LS991 is a soft-brick, which was easily fixed by using LGUP and a proper TOT with a factory reset. I was originally worried about testing my theory because most claimed the method of getting phone into diag mode and doing something wrong would hard-brick but I've had no such (bad) luck.

 

[ardian1899]

hahah, thanks! I really didn't expect to get too much response here. Most people only care if I was claiming to have achieved root, which I haven't. I did manage to downgrade to ZV6, which is the "rootable" rom but the few attempts I made at rooting caused a soft-brick and I had to restore a TOT to remove the soft-brick.

A lot of this info here was done by piecing together info others provided on this site so I was passing it along in the hopes this info could help another take another step forward.

From all my messing with this method it is fairly safe, worst I've gotten on two LS991 is a soft-brick, which was easily fixed by using LGUP and a proper TOT with a factory reset. I was originally worried about testing my theory because most claimed the method of getting phone into diag mode and doing something wrong would hard-brick but I've had no such (bad) luck.

Yeah.. root must be awesome, but anybody who use LS991 shouldn't ask much, haha.

So you can go down as far as ZV6? that's impressive. Is it using the similar method?

 

[lokichaos]

Yeah.. root must be awesome, but anybody who use LS991 shouldn't ask much, haha.

So you can go down as far as ZV6? that's impressive. Is it using the similar method?

I spoke too soon on ZV6, it will install and boot to LG logo where it will load in an infinite loop. I tried doing a factory wipe from recovery but that didn't help and I had to restore a custom ZVA rom to get back to functioning. In the ZV6 root thread they mention a infinite boot logo is normal and they did a couple things to fix it but I had no luck. I'm guessing that although the rom works the anti-rollback remains at ARB 4 and is blocking certain functions.

I'm not a dev so this is all trial and error for me. custom roms based on ZVA do work, AFAIK. If someone needed to downgrade to a rom with unlocked sim then this method is perfect, for example.

 

[ardian1899]

I spoke too soon on ZV6, it will install and boot to LG logo where it will load in an infinite loop. I tried doing a factory wipe from recovery but that didn't help and I had to restore a custom ZVA rom to get back to functioning. In the ZV6 root thread they mention a infinite boot logo is normal and they did a couple things to fix it but I had no luck. I'm guessing that although the rom works the anti-rollback remains at ARB 4 and is blocking certain functions.

I'm not a dev so this is all trial and error for me. custom roms based on ZVA do work, AFAIK. If someone needed to downgrade to a rom with unlocked sim then this method is perfect, for example.

I see that.
Very nice, thanks

 

[thebeartian]

I used to find a method to make gsm work in a ZVI version and about to give up. Your post is really so helpful. (It's really unexpected that there still have active threads about that old model)

 

[kwisatzhaderach]

Are the files still available?

Hey @lokichaos I recently picked up a Sprint G4 LS991 with DVI and all I'm hoping to do is unlock it for use on Verizon. Your guide sounds like exactly what I'm trying to accomplish but all of the links on the linked guide by @tabp0le are now broken (maybe I should ask them?). Do you happen to have a copy of the various needed files? I'm fairly happy with my G2 (lol) but the G4 seems like a solid improvement.

 

[poog]

just wanted to share my experience in downgrading my G4's software version and want to let everyone know it's possible.

using the guide by @tabp0le here: https://forum.xda-developers.com/sp...-mellowmallow-debloated-60fps-camera-t3358340

Depending on which current version you are on you will need the official TOT to get the process going. Once you pull your cable use the MellowMallow .img (ZVB) provided by tabp0le in his original guide and his diag commands.

I have successfully downgraded two ls991's to ZVB using this method. I do not know if this will work on other variations on the phone. THE KEY POINT IS THAT I AM VERY SURE THAT WHILE ON ZVI MY ARB WAS ON ARB 4 AND I WAS ABLE TO SUCCESSFULLY DOWNGRADE TO A LOWER software. Here's the thing, my ARB STAYED THE SAME so while ZVB is techincally ARB 2 my ARB stayed at 4.

with this in mind, you should, be able to downgrade to ZVA. I have not tested going from ZVI to ZVA so anyone willing to you will be trying the downgrade at your OWN RISK! I cannot assist you if you brick your phone but at this point I don't think too many people are worried about bricking the phone especially how cheap you can pick one up. the problem remains that you will still be on a higher ARB and the existing root methods were all done on a ARB <=2 .

quick guide (using tabp0le's original instructions):

0. if you haven't yet, read tabp0le's post, download all the files including LGUP and the official TOT for whatever version you are on (if you are on ZVI then download the ZVI.tot)

1. place the ZVB .img custom rom on tabp0le's post in your internal storage default folder. I will say the MellowMallow rom he provided is a a little buggy but the trade-off to be back pre security patch for 6.0 and unlocked sim card was worth it. make sure you use the right rom for your phone. If you have a global phone use the global rom/img. I haven't tested it yet but once you are back on ZVB you should be able to flash the official ZVB TOT so you can have a completely stock LG G4 with ZVB.

2. Place phone in diag mode by dialing ##DIAG# on dialer.

3. hook your phone into pc and change your usb mode to "charge only"

4. open up LGUP, if you have all your drivers installed from tabp0le's post then you should see your phone/version pop up.

5. select the TOT for your installed version on your phone, for me it was ZVI. hit start.

6. THIS IS WHERE YOU NEED ABSOLUTE ATTENTION TO DETAIL. Your phone will reboot. Keep an eye on the completion percent. 9% is the magic number. I would recommend watching your phone though. As soon as it says "COM XX" in green YOU PULL THE USB PLUG. if done right when it pops up, you would have pulled it right at 9%. if you are late, you risk bricking your device. However I will say that I did pull it at 11% before and all I did was replug the USB and allow the software version to update/reboot my phone. everything was fine and I attempted the whole process again successfully. if you just zone out and miss the sweet spot no worries, just allow the software to update and attempt the whole process again, DO NOT TRY TO STOP THE SOFTWARE UPDATE ONCE IT'S PAST 9%.

7. did you nail it at 9%? GREAT! continue on.

8. close down LGUP and open up a command prompt and navigate to the folder with "ports.bat" from tabp0le's post. run ports.bat. the instructions are word for word from tabp0le's post so I will just quote them.




here are the commands to flash based on version:
US ROM:

GLOBAL ROM:


if done correctly the command will "process" for a minute, it will look like nothing is happening, but that's a good thing! wait for the # to re-appear after about 3 to 6 minutes. once it does type "LEAVE", unplug your phone and reboot.

VIOLA! you should be on ZVB! hope this helps give this underrated phone some new life for those out there who gave up on it.

to check your version, download Hidden Menu APK
open it up after install and select:
* SVC Menu --> Version Info

https://androidfilehost.com/?fid=745425885120746375

update next post below

Great post, but the problem I think now seems to be the files are not available for download now on tadpole's mellow mallow thread for ZVB

 

[zamiel2112]

follow up post:
(custom) rom image using above method and everything went fine! I know there aren't a lot of G4 users out there left but hey, it's something..

*WARNING* Again, this is a highly untested process, your risk for brick is very high. Know that before you proceed *WARNING*

just download whatever rom you want and place it in your root internal storage folder.

when you get to



you will, instead, replace "rom_name" with the name of the (custom) rom you are trying to install. so, for instance, your rom name is "ZVAUltra" you will use:



for simplicity sake you can just rename the rom before you put it on your sd card to crom.img or something.
Right now, my LS991 is running UltraPOP AOSP created by @Agimax, his thread:
https://forum.xda-developers.com/sprint-g4/development/rom-mm-ultrapop-aospish-v1-0-t3351164

Bugs:
depending on the rom, you may have some buggy responses. I now have a constant "sd card is corrupt error" so your mileage will vary with this method. working on fixing this. I have NOT tested changing android versions ( android 6.0 to 5.0, etc...) so you will be DOING SO AT YOUR OWN RISK.

edit: more bugs. Once your apps start to update, dialer codes won't work properly (can't put phone in DIAG mode), bluetooth no longer works and you'll have some issues with SD showing up as corrupt. still researching. I might attempt a downgrade to ZV6 stock rom and root (I can dream, can't I?)to see how it goes. updates to come!

the only fix for the dialer code and the other issues is to format your phone either from "backup and reset" option in settings or through recovery mode. don't let your phone update! Put it in airplane mode or take out your SIM card. if you want to return to ZVI follow the steps outlined above with LGUP except this time just allow the update to finish and your phone will be on the latest software version.

hey I am recent LG G4 (ls991ZVI) acquiree I tried to download the linksfrom the other guys post, but they were all expired. Can you or anyone help me get this phone rooted I need a starting point.