[PSA] **WARNING** DO NOT TRY TO DOWNGRADE YOUR G4 BOOTSTACK (in USA at least)

[Dyscalculic]

No one has stepped up to answer the VZW question unfortunately.

For your purposes, though, it doesn't sound you are downgrading, just re-rooting and upgrading, so really this warning shouldn't have anything to do with your plan.

To be clear, I am trying to unroot (not re-root) 11A and upgrade to 13B and then root to 13B. Just trying to be safe than sorry. I have an exact replica of my current 11A rooted phone that I can extract the unrooted 11A stock image from, and will then apply to my current phone.

Happy to share that image if if there is interest and anyone asks and points me to the right file host. I haven't seen many Verizon 11A untouched stock images in the G4 threads.

I am happy to be the guinea pig and test out the service codes to check the VZW antirollback versions but don't know where to start. I have tried the AT&T hidden menu codes, but nada. I'm going to try some hidden menu apps but don't think that's a recognized way to go.

 

[waylo]

To be clear, I am trying to unroot (not re-root) 10A and upgrade to 13B and then root to 13B. Just trying to be safe than sorry. I have an exact replica of my current 10A rooted phone that I can extract the unrooted 10A stock image from, and will then apply to my current phone.

Happy to share that image if if there is interest and anyone asks and points me to the right file host. I haven't seen many Verizon 10A untouched stock images in the G4 threads.

I am happy to be the guinea pig and test out the service codes to check the VZW antirollback versions but don't know where to start. I have tried the AT&T hidden menu codes, but nada. I'm going to try some hidden menu apps but don't think that's a recognized way to go.

Oh yes I mistyped. Unroot, rather than reroot [emoji2]

You won't trip the anti rollback with your plan.

 

[heathenasparagus]

I'm confused. this is my phone. Can I use the KDZ exploit?

https://www.dropbox.com/s/q5y7969kj2ntklo/2015-12-14 14.31.31.png
https://www.dropbox.com/s/ojeg8axoguxxuvn/2015-12-14 14.31.36.png

 

[waylo]

I'm confused. this is my phone. Can I use the KDZ exploit?

https://www.dropbox.com/s/q5y7969kj2ntklo/2015-12-14 14.31.31.png
https://www.dropbox.com/s/ojeg8axoguxxuvn/2015-12-14 14.31.36.png

Your 'secret menu' does not list the antirollback #. Not all versions do, so it is unknown. Where did you obtain the phone from? What carrier? The antirollback lock seems to be only on some US carriers.

 

[heathenasparagus]

Your 'secret menu' does not list the antirollback #. Not all versions do, so it is unknown. Where did you obtain the phone from? What carrier? The antirollback lock seems to be only on some US carriers.

This is a European G4 bought in Israel.

 

[liyafe1997]

have you tried to flash TOT files to recovery it ?

 

[JamaicaNater]

So if try to flash v10c on my h815 V10-TWN-XX I will brick it?

 

[channeledbymodem]

Depends. How did you load the marshmallow rom? If you did not upgrade the bootstack, you could be fine downgrading. Most roms do not include a bootstack upgrade and this is flashed separately.

You could try flashing micro's stock 10n rom only. This doesn't touch the bootstack.

I think you are saying this would work?

I root and install twrp on h811 stock 10n.

I flash micro's 20i without updating the bootloader.

Later I can downgrade to micro's 10n as long as I have left the 10n bootloader in place all along?

 

[waylo]

I think you are saying this would work?

I root and install twrp on h811 stock 10n.

I flash micro's 20i without updating the bootloader.

Later I can downgrade to micro's 10n as long as I have left the 10n bootloader in place all along?

It's a bit unclear to be honest.

#1 - I don't know if the 10n bootstack is compatible with the MM system... it might give a security error if it is mismatched. That's not a huge deal, just flash back the older system. Or flash the newer bootstack.

I've been following some of the MM threads, and I don't know what happens if you try to flash the 10n bootstack on top of a 20i bootstack, but some users have reported flashing back to 10n (not always clear on the method they are using) without problems. Autoprime has called this v2 antirollback, which is the same version as the 10n bootstack. We're not downgrading if moving between 10n and 20i, just moving laterally, so it could be okay.

Some users MIGHT have used the LG tool to flash back to lollipop, and if this works, then that would mean you can flash the 10n bootstack back without consequence.

 

[channeledbymodem]

It's a bit unclear to be honest.

Thank your for your thorough and *honest* answer

Would you agree then that there is no "sure" way to downgrade from marshmallow and that one should be very sure one wants to upgrade before doing so?

That said, I am about to configure a brand new G4 that will be coming to me on some version of LP. I'm inclined to stay with 10N since after KK every "upgrade" I've done has been painful, at least initially.

Would you venture an opinion as to whether marshamallow is worth it given the uncertainty of going back? I won't hold you to it

I don't use wifi for calls or tethering, don't think I really need doze and can take or leave google now on tap so I think I'll be good with 5.1.1.

Thanks again.

 

[waylo]

Thank your for your thorough and *honest* answer

Would you agree then that there is no "sure" way to downgrade from marshmallow and that one should be very sure one wants to upgrade before doing so?

That said, I am about to configure a brand new G4 that will be coming to me on some version of LP. I'm inclined to stay with 10N since after KK every "upgrade" I've done has been painful, at least initially.

Would you venture an opinion as to whether marshamallow is worth it given the uncertainty of going back? I won't hold you to it

I don't use wifi for calls or tethering, don't think I really need doze and can take or leave google now on tap so I think I'll be good with 5.1.1.

Thanks again.

Oh, looking specifically at the autoprime MM thread, he's amended the first post (maybe on 2/15) to say:
1. *AntiRollback / QFuse V2* Safe to downgrade to 10N only.

So it appears confirmed that one can freely switch between LP and MM, provided you flash both system + bootstack, without risk of bricking.

I personally have not upgraded to MM. The doze feature sounds nice, but I installed a double-capacity battery on my G4 so aside from making it look hideous (kind of like the leaked G5 photo with the 'camera' pack), I have no worries about battery life. I have also either never had the lagging issues, or have lower standards and don't think my G4 is laggy, so any speed 'improvements' don't excite me. Yeah, it's anathema on XDA to not want the newest and 'best,' but I'm not one to create headaches when I don't have any to begin with.

 

[channeledbymodem]

Oh, looking specifically at the autoprime MM thread, he's amended the first post (maybe on 2/15) to say:
1. *AntiRollback / QFuse V2* Safe to downgrade to 10N only.

So it appears confirmed that one can freely switch between LP and MM, provided you flash both system + bootstack, without risk of bricking.

When I asked the same question in another thread Micromod referred me to the "kdz restore" in the thread you reference.

So, just for the sake of clarity, if I want to downgrade from MM, I can do a kdz restore to 10N, because the kdz will contain both the system and the bootstack?

Then once I'm on 10N again, I would oem unlock, root and install twrp from scratch.

What are people using to flash kdz's on this phone. The last time I did this I used LG Flashtool but the world seems to have moved on .

Confused about the difference between LG Bridge and LGUP.

 

[kalki1]

so i ended up bricking my phone .. -_-

now it wont turn on now or anything . anyone know to fix it ?

 

[sitonapanotis]

Im trying to root my h810, to my understanding this is only possible on LP but an ota was pushed without me confirming forcing me to upgrade to MM.

so now i have a stock OTA updated h810 that I would like to roll back to LP.
after typing in the dialer code I see that I am on anti-rollback version 2.

Unfortunately the tot method of rolling back is failing for me, although maybe its because my pc is windows 8.1.

Is it possible to flash a stock LP rom any other way?
Is it possible to flash a rooted LP rom while on stock OTA updated MM?
can anyone point me in the right direction if this is not the place for this question?

 

[justanutt]

Im trying to root my h810, to my understanding this is only possible on LP but an ota was pushed without me confirming forcing me to upgrade to MM.

so now i have a stock OTA updated h810 that I would like to roll back to LP.
after typing in the dialer code I see that I am on anti-rollback version 2.

Unfortunately the tot method of rolling back is failing for me, although maybe its because my pc is windows 8.1.

Is it possible to flash a stock LP rom any other way?
Is it possible to flash a rooted LP rom while on stock OTA updated MM?
can anyone point me in the right direction if this is not the place for this question?

I was able to flash the LP kdz with the LGUP app.

 

[sitonapanotis]

I was able to flash the LP kdz with the LGUP app.

there is no kdz for for the h810 (AT&T) unfortunately for me

edit:

Scratch that LGUP worked fine with the at&t tot instead of a kdz. Thanks for the direction!

 

[justanutt]

there is no kdz for for the h810 (AT&T) unfortunately for me

edit:

Scratch that LGUP worked fine with the at&t tot instead of a kdz. Thanks for the direction!

Glad I could help.

 

[wuvio]

i downgrade to 10N LP from 20i MM with LGUP, everything works well. only took 7 min in total. i hope this help more people

 

[stewie-droid]

Hi guys. on 811 from 20i to 10n it flashes but then phone gets stuck on t-mobile boot screen forever and wont' get past it. Any thoughts what's it going on with that.
I need to go back to LP for camera mod that does not work on MM.

 

[raptorddd]

This was not written anywhere specifically on the LG G4 forums that I could find. But every flash-addict needs to be warned. It is something you want to know before you continue tinkering.

Several users (myself included) have made the unfortunate mistake of attempting to downgrade their bootstack (for various reasons) to a former version.

DO NOT DO THIS (at least for the USA T-Mobile H811 version, and possibly other USA versions, per @autoprime)! It will result in a hard brick! Specifically, this results in the "Qualcomm QDLoader HS-USB port ( 9008 )" error. Connecting your phone to a PC will pop up with this active connection, but nothing else. There is no download mode. There is no publicly available fix as of yet.

This WILL happen both through KDZ restore as well as flashing bootstack .zips.

Yes, an official KDZ image can BRICK your USA phone, if you try to rollback.

This is in stark contrast to other manufacturers (i.e. Samsung), where the attempt to flash an older bootloader/modem/radio will simply fail, but your phone is not bricked.

I have conferred with @autoprime, who confirmed that with each OTA firmware release (on T-Mobile it was 10H, and now 10N), the version # increments. Flashing a lower version # will result in brick.

I have searched far and wide for a DIY fix. Without the proper firmwares in the right format, as well as the right flashing software, your phone is done and must be sent in for LG repair.

To check what antiroll-back version you are on, input this sequence in the dialer (T-Mobile and ATT) and scroll down:
*#*#244773825625#*#*

Flashing a bootstack version less than this # (through KDZ or zip) will brick the phone. You are free to flash anything equal or higher than the version listed.

EDIT:
The 20i MM update for the H811 is v2 antirollback. The 10n bootstack is also v2. So flashing between the 2 (returning from MM to Lollipop) should not hard brick the phone.

so if am in 20i i can safely go back to 10n KDZ.? and how would i update to MM 20i from 10N?