[Verizon Motorola Droid Turbo General] EjđiSixo:
Droid Turbo XT1254 Marshmallow->Lollipop downgrade (unlocking bootloader)COMING SOON?

*this is new thread because I started last as Q&A by mistake so first 2 pages may look off with posts and answers.

DOWNGRADING EXPERIMENT TOPIC

So as you may know , after upgrading to Marshmallow OTA, on locked bootloader there won't be any option to unlock bootloader (ever as some people say) , sunshine officially doens't support Marshmallow. The only option is to downgrade which again isn't possible on locked BL..

Or is it ?

Introduction - skip to DOWNGRADE

First of all I'm not an programmer , but have some experience with locked down motorola's bl's , firmware's ,downgrades and so on..

I'm sure when somebody says impossible, it doesn't really mean impossible, but rather not worthy to some. So in my case I bought the phone few days ago, wasn't fully up to date with infos on unlocking BL so didn't check FW version when buying , just after I checked and phone was updated on MM 1-2 days before buying it. On not unlockable BL phone will become useless to me very soon, while unlocked I would plan to have it for long period of time. It goes in Verzion's favour for me to ditch the phone and buy a new one except I'm not in USA , there are no Verzion services in my country and if there were I would never ever buy (again) anything from Verzion. Well I lived in Japan , and there is network Softbank which is well.. Imagine Verizon but on steroids when it comes to tying people down, locked bootloaders and software, insane fee's and so on.. Well that Softbank bough Verizon some time ago .. I was avoiding them at all cost, but on to the topic now.

DOWNGRADE - fastboot

I would like to invite everybody who is interested in this and who can help to participate in this. Every programmer that has time and can contribute would be greatly appreciated! In return I'm willing to sacrifice my phone and my time , even paying some reasonable donations.

While experimenting in the end I was able to flash all bootloader files from various different versions including all partitions related to it which gets upgraded. Even managed to flash XT1250 MM bootloader. Bootloader version DOES change in bootloader / fastboot ,But it doesn't mean ANYTHING. While downgrading , something else, possibly other parts of bootloader obviously search for match and there is more to it than simple bootloader , more experienced , chime on in here! SElinux enforcing? Verity?

(see attachments)

SU4TL-49 bootloader.img to motoboot flash - Successfully

SU4TL-49 manually flashing 1 by 1:

tz.mbn -[/B] Successfully

SBL1.mbn (bootloader) - [/B] Successfully

sdi.mbn - [/B] Successfully

fsg.mbn to mdm1m9kefs3 - [/B] Successfully

rpm.mbn - [/B] Successfully

emmc_appsboot.mbn to aboot - [/B] Successfully

gpt.bin to "partition" , it's the partitions info partition, people say it can't be downgraded or flashed cross versions. After some experimenting mfastboot failed but fastboot succeded, on some versions mfastboot worked - [/B] Successfully

What I can't get to downgrade / cross flash no mather which bootloader and combinations of firmware im on :

boot.img

recovery.img

system,img (sparse_chunk files)

I will go deeper, but hope that new full firmware SBF will be released soon in case of brick. Verzion is slow. I'm making my own full 6.0.1 xml.zip based on full flashable zip's , repacked system.img sparsechunks, rewrited the script but can't get to flash system files due to invalid signed image. Any help with that? It would also help already bricked guys because who knows when'll Verzion release it..

Downgrade OTA way , stock Android Recovery

While stock android recovery is pretty much useless, it can do software upgrades OTA on a fully stock system , which we on locked bootloaders and MM have.

In my opinion , the way is to trick stock recovery into thinking it's flashing ota, and that whole envieroment is like recovery is expecting it while it's actually flashing downgraded version full / close to full firmware in combination with you flashing some partitions manually through fastboot. OTA's contain only "patch" and just replaces files which get changed on new SW. Or even maybe reverse OTA downgrade?

I've made my own update.zip and signed it , but so far get footer size is wrong error so can't flash it .. Need more help here too..