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

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By waylo, Senior Member on 10th September 2015, 01:13 AM
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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.

EDIT 2:
The 20o MM update is v3 antirollback. Once you go 20o, you cannot go back.

For your flashing needs, I suggest you use LGUP and NOT LGFLASH, as LGFLASH will ignore the rollback flag and brick your phone without remorse!
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10th September 2015, 01:20 AM |#2  
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Twitter announcement re: above from @autoprime
https://twitter.com/utoprime/status/641747333470912512
10th September 2015, 02:31 AM |#3  
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Quote:
Originally Posted by waylo

Twitter announcement re: above from @autoprime
https://twitter.com/utoprime/status/641747333470912512

This is probable because of the huge security flaw in older versions...they probably dont want anyone returning to a vulnerable state...stagefright was a nasty flaw and i think moving forward we will be able to roll back to what we have now
10th September 2015, 02:33 AM |#4  
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so bad... but if my firmware version and the KDZ are the same? ex. H81510c with H81510c.kdz...... this still works???
10th September 2015, 02:44 AM |#5  
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Quote:
Originally Posted by Sj12345

so bad... but if my firmware version and the KDZ are the same? ex. H81510c with H81510c.kdz...... this still works???

Correct, shouldn't be a problem if they are the same revision.
10th September 2015, 03:03 AM |#6  
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thanks for the thread @waylo

I have checked the most recent international builds and all are still on "v0". Tho that could always change in the future... but as of today... "v0"

The original out of box Tmo h811 version was "v0"... after the first forced OTA it became "v1"... as of 10N it is now "v2".
I do not have access to the latest AT&T, Sprint, US Cellular or Verizon bootstacks (seems there are no new KDZ's for them and no one has dumped the files) so I cannot confirm if AT&T, Sprint, US Cellular or Verizon's latest OTAs also move it up to "v2" or if still on "v1".

Actually.. I'm not even sure if Sprint, US Cellular or Verizon got a 2nd OTA yet.. but I know AT&T has "10i". If any 10i users who are rooted could dump the bootstack for me and send it over I can confirm.

Latest I know of for Sprint is ZV5.. thats "v1". US Cellular.. not sure.. but 10C was "v1". Verizon... again.. not sure what latest is.. but 11A is "v1".

*edit*
just checked US991 10D... still "v1".
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10th September 2015, 03:41 AM |#7  
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Quote:
Originally Posted by autoprime

thanks for the thread @waylo

I have checked the most recent international builds and all are still on "v0". Tho that could always change in the future... but as of today... "v0"

The original out of box Tmo h811 version was "v0"... after the first forced OTA it became "v1"... as of 10N it is now "v2".
I do not have access to the latest AT&T, Sprint, US Cellular or Verizon bootstacks (seems there are no new KDZ's for them and no one has dumped the files) so I cannot confirm if AT&T, Sprint, US Cellular or Verizon's latest OTAs also move it up to "v2" or if still on "v1".

Actually.. I'm not even sure if Sprint, US Cellular or Verizon got a 2nd OTA yet.. but I know AT&T has "10i". If any 10i users who are rooted could dump the bootstack for me and send it over I can confirm.

Latest I know of for Sprint is ZV5.. thats "v1". US Cellular.. not sure.. but 10C was "v1". Verizon... again.. not sure what latest is.. but 11A is "v1".

can you share the method to know if the bootstacks change with each ota?
I am pretty sure ATT has anti rollback on!
or give me the code for dump the bootstack
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10th September 2015, 04:59 AM |#8  
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Quote:
Originally Posted by jamesd1085

This is probable because of the huge security flaw in older versions...they probably dont want anyone returning to a vulnerable state...stagefright was a nasty flaw and i think moving forward we will be able to roll back to what we have now

That's a nice thought, but it will not be borne out until the next OTA comes out and we check the version. I wouldn't recommend you act on this supposition unless you have the time for a repair and a backup phone.
10th September 2015, 08:43 AM |#9  
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Quote:
Originally Posted by waylo

That's a nice thought, but it will not be borne out until the next OTA comes out and we check the version. I wouldn't recommend you act on this supposition unless you have the time for a repair and a backup phone.

It was just a shot in the dark...but i always read and am very careful what i flash...but on the other hand my best friend has a good bit of experience with Android repair and a very pricey computer and a rather nice jtag device...I'm just hoping lg isn't turning the way of Samsung and trying to block out development as it will be the reason if i ever leave lg devices...locking out development is a boner killer and i wont think twice but to move to more open oems...lol
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10th September 2015, 03:40 PM |#10  
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I have a Sprint variant and we have only had one OTA as of right now.

Sent from my LGLS991 using Tapatalk
11th September 2015, 12:11 AM |#11  
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Quote:
Originally Posted by autoprime

thanks for the thread @waylo

I have checked the most recent international builds and all are still on "v0". Tho that could always change in the future... but as of today... "v0"

The original out of box Tmo h811 version was "v0"... after the first forced OTA it became "v1"... as of 10N it is now "v2".
I do not have access to the latest AT&T, Sprint, US Cellular or Verizon bootstacks (seems there are no new KDZ's for them and no one has dumped the files) so I cannot confirm if AT&T, Sprint, US Cellular or Verizon's latest OTAs also move it up to "v2" or if still on "v1".

Actually.. I'm not even sure if Sprint, US Cellular or Verizon got a 2nd OTA yet.. but I know AT&T has "10i". If any 10i users who are rooted could dump the bootstack for me and send it over I can confirm.

Latest I know of for Sprint is ZV5.. thats "v1". US Cellular.. not sure.. but 10C was "v1". Verizon... again.. not sure what latest is.. but 11A is "v1".

*edit*
just checked US991 10D... still "v1".

Does this also apply to TOT files? Say we upgrade to ZV6 when it comes out. Can we use a TOT file to flash to ZV5?
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