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Downgrade from B9xx to B8xx

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#1
ScutulatusCrotalus

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Hello,

I am kinda lost here. Most downgrade tutorials were written before ICS came to our devices, so I do not know if any of those are outdated or not. Is there any possibility to downgrade from B934 to B892(or B884, B885) to make official OTA updates available as on untouched devices and fully working?

My current state is that I do have - CWM, rooted B934, and also backup files for my imei from B892 (only for B892, I have rooted and flashed my device after B892 update came for it).

Could someone clarify what steps are valid to downgrade? I am not happy with ICS on it, battery life is shorter and UI is not that responsive as on B892 (and also my previous ZTE Blade had much more responsive UI than my G300).

THank you so much.

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#2
wwwjunk

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I downgraded yesterday from b934 to b882.
Did as i always do, and always work.

Change imei to 0
flash rom i want via dload folder
restore original imei (of course after rooting the device)

PS: i've changed between lots of roms (almost all of them) this way and was always successful. I flash the rom i want directly

Edited by wwwjunk, 25 August 2012 - 11:18 AM.

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#3
ScutulatusCrotalus

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I downgraded yesterday from b934 to b882.
Did as i always do, and always work.

Change imei to 0
flash rom i want via dload folder
restore original imei (of course after rooting the device)

PS: i've changed between lots of roms (almost all of them) this way and was always successful. I flash the rom i want directly


So if I understood well - by downgrading from any ROM I have to zero my IMEI by installing an update, then flash any ROM I want and that it is - after it I have to restore my imei via 5irom.

There are few things that I do not understand. Does IMEI backup depend on specific version of ROM - or does it depend on baseband?

If I do have only B892 IMEI backup and if I only want to go back to stock B892, I presume that I would zero my IMEI, flash it straight, restore my original IMEI I backed up it before and I am done, right? Should be restoring done only when I am downgrading, right?

The last thing that Daz has placed B892 on his mirror and it's located in cn folder - should I be concerned if this version of ROM is not UK? Just want to have clean vodafone UK rom, unrooted.

if I summarize it:
- zero ROM
- flash B892 straight on my G300, no middle package
- restore my B892 imei backup
- done

There's no need to go to B892 via B885 or B882, right? I do only have B892 imei backup.

Sorry for my questions. I just want to be informed and to be sure. Also sorry for my poor english language.

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#4
Emmepi

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Take a look at the lasts posts here : http://www.modaco.co...aseband-109808/

Just put the right rom to SDCard in the right folder, shut off your G300, and power it on with (vol+ vol- power) combo

I've downgraded from b934 to b888 without problem.
No IMEI lost during downgrade

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#5
luvvt

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Your backed up imei number can be used to restore on any rom you flash, B8xx or B9xx.

You have to use the downgrade 5irom files to zero your imei before you can downgrade from ics B9xx roms back to gingerbread B8xx roms. Also to flash across ics B9xx roms use the downgrade 5irom only if the Middle package doesnt work. (all these are in the pinned threads)

As for the ota updates, If you install B882, root, restore imei, you will be able to use ota upgrades. However i have found that ota updates will not work if you have cwm installed.

if I summarize it:
- zero ROM
- flash B892 straight on my G300, no middle package

- root (note you will probably have to do a factory reset to re gain root after you have installed root)
- restore my B892 imei backup
- done


Correct Please dont forget to make multple backups of your imei number and clearly mark them as being your original number

Edited by luvvt, 25 August 2012 - 09:19 PM.

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#6
b4da55

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Does middle rom zero imei

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#7
luvvt

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no, hang on a minute im looking for the link

ps: re read my post i edited it

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#8
luvvt

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Its very important to read and understand this method before you try

https://docs.google....QHNo/edit?pli=1


Ps the middle package is for ics roms only

Edited by luvvt, 25 August 2012 - 09:34 PM.

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#9
ScutulatusCrotalus

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Well, tutorial from
- Emmepi leads to same solution, as was my upgrading to B934 - big update.app, did not work, then middle, then big update.app, then vendor update.app.
- tutorial from google docs does this the same, but with zeroing IMEI. Why is it so?

luvvt: You've written that my IMEI backup from B892 will be compatible with all B8xx ROMs - so if I downgrade to B882, my IMEI was zero, then I should use my IMEI backup. Or should I upgrade then from B882 to B892 where my IMEI backup will be usable?

Sorry for having too many questions, just want to know everything.

Edited by ScutulatusCrotalus, 25 August 2012 - 09:45 PM.

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#10
luvvt

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I dont understand your last post.

your trying to downgrade from B934 to B882 yes ??

Edit:

Your backed up imei will be compatible with all roms B8xx gingerbread and B9xx ics

Edited by luvvt, 25 August 2012 - 09:54 PM.

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#11
ScutulatusCrotalus

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Yes, I am.


I'm just a bit confused, because there are two tutorials - Which one should I use?

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#12
luvvt

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This link is the g300 downgade 5irom folder

https://docs.google....QHNo/edit?pli=1

It contains a hacked version of 5irom that will zero your imei. This is needed to downgrade from B9xx roms back to B8xx roms (you will have to do this)
Your backed up version of 5irom you will use to restore your imei to its original number

Ignore the middle package as this was specifically released with B927 B926 ics (I cant rememberwhich one) to allow upgade across ics roms

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#13
ScutulatusCrotalus

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Last thing that pushes me from downgrading is missing vendor update.app from B8xx ROMs. Without that I won't have original Huawei toggles and OTA from Vodafone won't work.

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#14
tcpaulh

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You don't need to zero your imei or change it in any way in order to downgrade. Taking a backup of it is a sensible precaution though.

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#15
luvvt

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Yep thats the problem no vendor updates and no toggles.

I have downgraded mearly to get the official ics ota upgrade. i only want to see what it contains for me as all the ics roms are world wide or chinese versions and i am in nz.

Im surprised though that you dont like B934 i found it much better than gingerbread, Check your setting especially the 2d redering, as this will slow thing up considerably

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#16
luvvt

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You don't need to zero your imei or change it in any way in order to downgrade. Taking a backup of it is a sensible precaution though.


Are you sure

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#17
Rico_89

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Well if you have a nandroid backup, of your previous GB installation, then after you downgrade to your desired B8XX rom, you could then recover your GB back up.

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#18
tcpaulh

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@luvvt, Yep at least on my phone and other positive reports

Edited by tcpaulh, 25 August 2012 - 10:29 PM.

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How To Provide Error Logs

 

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#19
Rico_89

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@luvvt, Yep at least on my phone and other positive reports


Huh... :blink: ..downgrade without middle app or imei hack??

Never heard of that before.

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#20
ScutulatusCrotalus

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Im surprised though that you dont like B934 i found it much better than gingerbread, Check your setting especially the 2d redering, as this will slow thing up considerably


Well, I really like ICS and JB, but official B934 is not that fast as I expected. Just realized that GB on G300 was much faster and ICS on ZTE Blade was also faster.

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