xboxscene.org forums

Xbox360 Forums => Xbox 360 Hacking Forums => General Technical Hacking Discussion => Topic started by: p3pp8 on January 10, 2010, 09:23:00 AM

Title: Downgrade With Cpu Key
Post by: p3pp8 on January 10, 2010, 09:23:00 AM

Hello, is it possible to downgrade from 8955 if i got the cpy key? i'd like to build a clean 1888 build and update my cb with the correct efuse count that should be around 7, would my board boot again with it?
Thanx to anyone who wants to answer!

Title: Downgrade With Cpu Key
Post by: p1nky2oo7 on January 10, 2010, 10:52:00 AM

it won't work, sorry

Title: Downgrade With Cpu Key
Post by: p3pp8 on January 10, 2010, 11:08:00 AM

Oooh man, many thanx for the answer, i'm wasting time trying to change valkues and reflash nand, can you explain me why it wouldn't boot? there is a way to let it boot again? i've a 8507 good dump, could i insert my kv and build a degrader nand with the right ldv value?
Thank You, for real!!!

Title: Downgrade With Cpu Key
Post by: No_Name on January 10, 2010, 02:13:00 PM

How many times is this question going to have to be answered??

It wont work because they blew a second line E-Fuse which locks out the exploitable CB section of the bootloader.

Title: Downgrade With Cpu Key
Post by: crash_2012 on January 10, 2010, 05:53:00 PM

if you try it, your console will get a rrod, with an error code of 0022.  it just doesnt work.  ive tried it cuz ive wanted to see what would happen.  i had a spare console that was missing the dvd key, so it wasnt a loss to me.

Title: Downgrade With Cpu Key
Post by: p3pp8 on January 11, 2010, 03:11:00 PM

Ok, sorry for the noob question, the thing is that i haven't understood exactly how lockdown values and efuse burning works, so i thought that using cpu key and adjusting value for the cb section it would have booted, anyway my last idea was to use a downgrader image built using a kernel 8xxx with a CB 1940 and with the right ldv value for the cb, is it possible? it should works, does the unban method do this? So excluding old kernels, is it possible to make this board boot again, may be patching a good 8955 dump with my kv? What can i do, so the cpu key is useless as well.....
When you say a second line efuse do you mean the usual line 7, the one where ms burn a fuse at each update or a totally new one? I think i've to google a bit more.
Thanx anyway guys, sorry to bother with really lame questions (IMG:style_emoticons/default/wink.gif)

Take care!

Tried out to use a good nand with CB 1940 and kernel 8453(it should be as the original one that i've lost) patched with my KV, created a downgrader image with degraded and flashed guessing a good ldv value for the CB, this time i got a 0110 rlod, it should depends to a wrong ldv count, isn't it?
Thanx for the help guys!

Title: Downgrade With Cpu Key
Post by: Elspero on January 11, 2010, 03:47:00 PM

You can't downgrade. If you want it to work again flash back the original 8955 nand you dumped (do you have a copy, right?).
It has been said a million times: the exploit works only if the console hasn't been upgraded. Once done that, there's no way back.

Title: Downgrade With Cpu Key
Post by: p3pp8 on January 11, 2010, 03:55:00 PM

I don't wanna boot xell, i just want to boot my console back normally, i know there is no way to boot xell on updated console becoz of the burnt efuse line, my problem is that i've lost my original 8955 dump, i only got an old 1903 cb dump and a 8507 from another console, so my question is, is it possible to bring it back to boot again flashing a new CB nand i.e the 8507 above and not the old one as i perfectly understand old ones cannot boot.
Thanx dude!

or at least rebuild a 8955 dump and patching it with my original kv.....

Title: Downgrade With Cpu Key
Post by: Elspero on January 11, 2010, 04:34:00 PM

QUOTE(p3pp8 @ Jan 11 2010, 11:55 PM)

or at least rebuild a 8955 dump and patching it with my original kv.....

I guess you could rebuild a 8955 nand. Flash Dump Tool should allow you to encrypt a donor nand with your keyvault.bin and your config.bin, using your cpu key.
To decrypt the donor nand you need their cpu key.
I haven't personally done it, so I can't guide you through the process...

This post has been edited by Elspero: Jan 12 2010, 12:35 AM

Title: Downgrade With Cpu Key
Post by: p3pp8 on January 12, 2010, 12:17:00 AM

Thank you mate, there is an already decrypted nand version 8955 at xbins and i've googled a bit and read something about a ibuild command with a custom build.py to rebuild first a 8498 and then a 8955 donor, i've a xenon board so it should be easier, i'll try to do something with it, if success i'll write something like a tutorial.
Thank you so far....

Title: Downgrade With Cpu Key
Post by: p3pp8 on January 15, 2010, 02:14:00 PM

Just  to let someone knows it, i've tried to rebuild out from my orignal 7xxx dump a good 8955 nand using ibuild but after googled a bit(and tested on the board too) i've discovered that even if you use an old original dump to rebuild 8955 it is impossible to rebuild a perfect good 8955 dump, the only way is having the original one becoz many parts of the nand are signed by a special key that only ms knows i.e. the first hash located at CB's header, ibuild generate it randomly that is not good for an updated board(still good for old ones), so if you've lost your 8xxx dump you've lost your board, at this point i'll try to sell it out through ebay just as spare parts, maybe someone can find it useful.
Good bye!