yashsingh1/xdaforums huggingface dataset:
[Transformer TF300T General] Q-Logic:
I can confirm that this method 101 % works. :good:

I have migrated from custom ROM 4.2.1 to factory 4.2.1.

After final reboot I lost root, but rooting afterwards gave me rooted factory 4.2.1. No problems at all.

Thanks for this.
[Transformer TF300T General] Keshukas:
+1 works
[Transformer TF300T General] funnel71:
OK, I have a question. I see this works with full ROMs from Asus, good. What about TWRP backups?

So, before I upgraded to 4.2.1, I took a TWRP backup of 4.1.1 latest v20 build. If I restored that backup via TWRP, would it work? Would the bootloader revert to the older one (with the USB icon)? My backup did include the boot partition, but I didn't know if this would brick the device.
[Transformer TF300T General] MrsColumbo:
Just to make sure ...

Have you actually downgraded from 4.2.1 to 4.1.1?

I'm on 4.2.1 (10.6.1.8; Energy Rom) at the moment and eager to browse all those nice custom roms that are based on 10.4.x.x. like cm 10.1 & co.

Since the 4.2 upgrade rearranged the file system i'm afraid of messing it up when reverting to pre-multiuser-versions ...

Also i'd love to have this nvflash brickproof thingie ...

You think I could give this a go?
[Transformer TF300T General] Q-Logic:
To be honest - I'm not sure, I didn't downgrade, let pjc21 say did he. I would be afraid to do mess with file system just like you.

But I would be interested to try this if his downgrading method works.
[Transformer TF300T General] pjc21:
I'm not sure here, but would think no as the new update has a different file system arrangement. I myself would not try this as I really have no idea what would happen.
[Transformer TF300T General] pjc21:
Yes I have downgraded from 4.2.1 (10.6.1.8) to 4.1.1 (10.4.2.20) and I have also downgraded through all the JB firmware back to the first JB firmware that came out 10.2.4.9 -28/08/2012- not that many people would want to go back that far but I was attempting to go all the way back to an ICS bootloader & firmware so I could access NVflash and become brickproof as my tab came with JB pre-loaded. When attempting to go from a JB bootloader & firmware to an ICS one there is a signature mismatch which I have not looked into as yet and am not sure it would even be possible to modify this to get a match. I will have a look when I get the time and look at the differences between the JB & ICS signatures to see if it might be possible to modify these.
[Transformer TF300T General] MrsColumbo:
Works fine

Witch much satisfaction I can confirm this working. Had to sideload the update zip, though, 'cause I forgot to copy it to my external micro sd card. in the course I ****ed up the update (progress indicator not progressing, so i did a vol-+power-reset, subsequently rom did not load), but adb-d recovery again, inserted micro sd and did the update (downdate) to 10.4.2.20. running cm 10.1 nightly now.

Yeah, this brickproof mod sounds really good. I wouldn't want to miss up on jb's smoothness, though. IMHO JB and ICS are worlds apart. Maybe those guys give it a go with a 4.2-brickproof-mod one fine day :)

Thanks pjc21 for this outstandig work. This is what Android OS is about: being able to explore all possibilities of a fine piece of hardware you actually own instead of being led on a leash by a corporation. :good::good::good:
[Transformer TF300T General] treo4life:
This worked pretty easy, returning from 4.2.1 ( 10.6.1.8) I flashed the 4.1.1 (10.4.2.20) blob through fast boot,then flashed twrp 2.3.3.0 in fast boot, rebooted into recovery restored my 4.1.1 backup and all is well.
[Transformer TF300T General] wetbiker7:
Please update us on your progress. Everything I've read says that going back to ICS for NVFlash cannot be done if the tablet came with JB. Thanks.

Sent from my LG-LG855 using Xparent SkyBlue Tapatalk 2
[Transformer TF300T General] treo4life:
He stated you cannot go back to ICS in the first post,, but you can switch JB firmware pretty easy.
[Transformer TF300T General] wetbiker7:
Exactly. But........ he also said he was going to try and modify the signatures to see if he can get them to match. If he can succeed, it will be a huge breakthrough.

Sent from my LG-LG855 using Xparent SkyBlue Tapatalk 2
[Transformer TF300T General] treo4life:
That's true, don't know if he is going to try to tackle that one though.. would be nice to have the option...
[Transformer TF300T General] wetbiker7:
No doubt. Hopefully he'll continue working on it.

Sent from my LG-LG855 using Xparent SkyBlue Tapatalk 2
[Transformer TF300T General] ntunit:
I just received my new tablet ... Need to downgrade to 4.1.1 to be able to run AOSP Rom.

Thanks for the procedure. I will give it a try.
[Transformer TF300T General] CorkedA:
I'm getting command write failed unknown error, what am I doing wrong?
[Transformer TF300T General] pjc21:
What command do you get the error on?
[Transformer TF300T General] CorkedA:
fastboot -i 0x0B05 flash system blob

sending 'system' (800923 KB)...

FAILED (system read failed ( too many links ))

finished. total time: 0.002s
[Transformer TF300T General] pjc21:
Not sure why it's failing, I have not seen this error before. Does fastboot see your device ok?

Maybe a bad/corrupt system blob? You could try and re-download and see if that works.
[Transformer TF300T General] CorkedA:
Late response, sorry. But I got it flashed finally, it just didn't like my front usb ports for some reason, now I'm stuck at boot screen, It's been booting for about 5-6 minutes, I'll give it 20 minutes.
[Transformer TF300T General] markymark567:
No it will not restore your bootloader. Twrp cannot back up your bootloader. Boot partition refers to backing up the kernel partition I believe. But you should be able to downgrade then restore your twrp backup
[Transformer TF300T General] pastorbob62:
It does work

Great procedure! I did this with the US version. I thought I had trashed my tablet after installing a custom ROM. It would go as far as the ASUS boot screen and then lock up. So I downloaded the latest stock ROM and followed your steps. Worked flawlessly!

The only difference is I don't see my serial number when I do this. It doesn't seem to affect anything though because it does the burn without issue.

Thank you again for providing this.

:D

Bob
[Transformer TF300T General] lk2l:
look like you guys know the twrp better than me...

may I ask you some help, today I try to installa cyanogen 10.1 and (obviously) stack at the asus logo... at this point I restore only the boot of the stock version (4.2.1) trought twrp and now I have the cyanogen logo running but it doesen't start yet, did you try somthing like this?
[Transformer TF300T General] ntunit:
Did you clear Cache and Dalvik Cache ?
[Transformer TF300T General] pcoussa:
Simply Awesome!
[Transformer TF300T General] pjc21:
No I have not tried to install CM 10.1 on the 4.2.1 bootloader but have read comments from others that have tried but looks like at the moment this is not possible.

In order to install CM 10.1 you'll have to downgrade to 4.1.1 (10.4.2.20).
[Transformer TF300T General] pcoussa:
I have tried installing CM10.1 on 4.2.1 and couldn't get it to work. I would just hang at the Asus screen.
[Transformer TF300T General] Jamalsid:
Has anyone tried downgrading their 10.6.1.8 JB bootloader to the 10.4.2.20 JB bootloader using Sbdags's flashable zips here?
[Transformer TF300T General] Rhian:
It worked after a little scare

I wouldn't recommend that. As mentioned in other posts, the filesystem changed.

My adventure:

I did the steps outlined in the OP. I was on 10.6.1.8. (I did a full wipe of everything, including internal storage)!

It was scary though, mine did get stuck. I waited 15 minutes after the blue bar had been filled! (So the total time passed was 26 minutes!) Then powered off, of course resulting in the FAILED below:

fastboot -i 0x0b05 flash system blob
erasing 'system'...
OKAY [ 0.384s]
sending 'system' (799748 KB)...
OKAY [142.182s]
writing 'system'...
FAILED (status read failed (Unknown error))
finished. total time: 1606.212s

I do not know the reason for it to get stuck, but at least it didn't brick!

However, my pad rebooted, so I powered it into the boot-loader and surprise surprise there was a USB icon! From there I completed the steps and eventually my pad was a 10.4.2.20!

The fun didn't last very long though... It was late last night when finishing this downgrade and when setting up the system this morning I noticed some oddities.

My google account didn't fully connect, I regularly started to get a message stating "Refresh failed" and the play store either failed to connect completely or started to connect then fail.

I figured this had something to do with the never ending wait. I've tried a couple of different ROMs on the 10.4.2.20, but all seem to give the same issue. Flaky WiFi connection websites not loading and more of these issues.

I tried the procedure once more, but the effect ended up being the same (never ending writing, I waited about 20 mins after the blue bar had been filled!), I had to power it off and when finished with the rest of the procedure I had these connectivity issues again.

fastboot -i 0x0b05 flash system blob
erasing 'system'...
OKAY [ 0.349s]
sending 'system' (799748 KB)...
OKAY [139.567s]
writing 'system'...
FAILED (status read failed (Too many open files in system))
finished. total time: 1764.347s

I ended up putting the 10.6.1.8 update on my MicroSD and updated through the usual update system. (Note that I DID redo the procedure without adding a recovery for the update to work. If you do add TWRP, the update will just reboot into TWRP, rather than processing the update).

Back on 10.6.1.8 everything works fine and dandy! (Albeit with building up lag as before.)

So, my conclusion is, certain models (mine is one of the newest black models, serial starting with D2, according to some sites manufactured 13/02/2013) might not be able to go back fully for whatever strange reason.

If there is anything I can do to help with this issue, please let me know.
[Transformer TF300T General] Soy_Filipo:
I have ADB setup, but I can't seem to get fastboot devices to work, but for some reason, when I reboot my device with fastboot using "fastboot -i 0x0b05 reboot" I can reboot the device, Am I doing something wrong?

---------- Post added at 05:13 PM ---------- Previous post was at 04:49 PM ----------

Which drivers are you guys using?
[Transformer TF300T General] emre1393:
not need unlock, just use asus rom zip

transformerforums.com/forum/transformer-pad-300-general-discussion/35335-successful-downgrade-4-1-1-hdmi-back.html
[Transformer TF300T General] pcoussa:
Went to that Url you posted. Seems the way he downgraded was all done on the tablet and no need to connect to the PC?!
[Transformer TF300T General] Rhian:
I'm not sure what is going wrong, but I'm guessing you are in the wrong mode when issuing commands.

ADB commands can only be used when booted in Android's OS. Fastboot commands can only be used when in the fastboot mode of your device. (I tend to think of fastboot as my BIOS).

As mentioned in the first post the correct command is:

fastboot reboot-bootloader

You can verify that you can actually communicate with the device (once in fastboot mode on your pad) by using:

fastboot devices

Note that the serial number mentioned with adb devices (while in Android) is the actual serial number of your device, in fastboot you do get a different hexadecimal code. (If you use TWRP to make a backup and check into its folders, you'll see TWRP/BACKUPS/<fastboot-serial>/<YourBackup>/... )

This is all documented in the very first post of this thread and works like a charm (provided you do have the USB drivers installed).

Use the search or the help topics to find out which drivers you can use in case yours don't work.
[Transformer TF300T General] Rhian:
Yes, that is indeed how it works if you do NOT have a recovery installed (I don't know about still being locked).

I tried and tested it. (Although I ended up with the same problems I mentioned before, the 10.4.2.20 kills my WiFi connectivity.)

What I had done...

I used the method in the first post here to get to stock 10.6.1.8 and did NOT add recovery and/or root at the end. So mine was really stock-stock and going into RCK mode gives the dead Android picture.

I copied the WW_epad-user-10.4.2.20.zip (from the downloaded Asus zip file) onto my microSD. Booted with it inside and got the system update notification in the notification area. I tapped it and got:

Next:

Then finally before the reboot:

The usual process of the official update happened (with the Android and star thingy first, then the blue bar updater) and finally booted into the setup wizard of 4.1.1.

Result:

I did this just to test the process and it worked for me. However, something in the 10.4.2.20 changes the way my WiFi works, because after using the WW_epad-user-10.6.1.8.zip to upgrade, the problems persist. I can only fix that by using the methods described in the first post here to get mine cleanly back on 10.6.1.8. Which makes me believe that mine was shipped with a different 10.4.2.20 or perhaps an intermediate version. I never checked the version before installing the OTA unfortunately...
[Transformer TF300T General] Soy_Filipo:
I'm actually in Fastboot mode but I don't see my device listed, I can tell the difference between adb and fastboot mode, I've been flashing with fastboot for a while now. I've actually flashed my TWRP without seeing my device listed using the fastboot devices command.

But I cant seem to flash the blob now.

I'm thinking its a drivers issue, I've used the drivers in Asus sync and universal naked drivers but no luck yet, maybe its windows?

PROBLEM SOLVED

You need to download the latest SDK

http://developer.android.com/sdk/index.html

the tools you need are in platform tools, you might wanna say that on the first post OP ;)
[Transformer TF300T General] Dr.Alexander_Breen:
Guys, now that is something interesting. That means I can flash back ICS and do NVFlash?
[Transformer TF300T General] funnel71:
No it doesn't. It will look successful when loading but when done, you will still be on jb.
[Transformer TF300T General] Dr.Alexander_Breen:
Oh, OK. Sad.
[Transformer TF300T General] pcoussa:
Did you try it anyway?
[Transformer TF300T General] nevarDeath:
Did this following the OPs instructions. Went from stock 4.2.2 down to 4.1.1 and was able to flash CM10 successfully :D I used the 10.4.2.20 firmware to do it.
[Transformer TF300T General] Insane PPC:
just wanted to say thanks for the guide, worked like a charm, i'll go back to 4.2.1 as soon as kernel source drops, but until then, rocking 3.4.6 cromi
[Transformer TF300T General] markymark567:
TF700 kernels are out bud. They make the tf300 lightning quick!!! You better upgrade again cuz your missing out hahahahahaha
[Transformer TF300T General] Kaptinkrunk:
how can i unlock 4.2.1??
[Transformer TF300T General] aerdely:
Download the unlock tool from asustek website. Also make sure what u are using it for if you no longer have warranty or just don't care and want roms and recovery then use it but if you have warranty remember it will void it asus will know automatically and you will no longer receive updates. Other wise just download from asus site install with file manager and run it pretty simple.
[Transformer TF300T General] Kaptinkrunk:
already done that maybe the when i rma'ed it maybe they put something to stop me from unlocking it?? the tool doesnt work? to downgrade you have to be unlocked? i have it on the sd and its popping up like its good for a downgrade...
[Transformer TF300T General] aerdely:
Don't have to be unlocked to downgrade. If you were unlocked when yo rma'd it and they fixed it your stuck because its still probably in there system as already being unlocked ie no warranty so it won't allow it again. Other wise not sure why it wouldn't work. They wouldn't purposly stop you only another possible firmware update would but they gave use the tool to use at our discression wouldnt matter to them because they only make more money when u send it in for rma after your unlocked.
[Transformer TF300T General] funnel71:
With the Asus unlock tool
[Transformer TF300T General] aerdely:
Also make sure you have network access won't work if don't
[Transformer TF300T General] Kaptinkrunk:
Awesome so I can downgrade it and unlock and the rest.. Or will it brick it because every downgrade I read says unlocked only... Its never been in locked eithr

KrunK Nook Color CM10.1 beta ThyrusHolo Black
[Transformer TF300T General] aerdely:
As far as i know wouldn't have to be unlcked now i've never done it my self but others have told me no need to in when you download the desired asus firmware, unzip it and rename it method i explained it to someone who wanted to reflash they're current version which was 10.6.1.8 and it work for them although it didn't fix the problem because theirs was a harware issue. Now you can try to downgrade while being locked with that method wouldn't hurt you'd just get the dead android on its back if the tablet denied it. Like said don't take my word for it haven't needed to do it my self just remember other explaining it that way and reporting success. If not then just unlock and use the adb method if feel like it the other is supposed to be safer though.

I will attempt it my self i'd like to know for sure too and i'm locked will let you know.
[Transformer TF300T General] aerdely:
Update it works just fine even if locked still posting right now and on 4.1.1

Good thing dont even have to rename downloaded unzipped and was already named correctly just copied from my sdcard to internal storage and remove my sdcard then update notification appeard which just went through the prompts and likean update just went through. Should be able to go as far back as 1st jb update but probably wont need to. Also got the prompt for and ota which is downloading then back to 4.2.1 good luck
[Transformer TF300T General] Kaptinkrunk:
Well downgrade worked but still can't unlock it ughhhh

Sent from my Galaxy Nexus using Xparent Cyan Tapatalk 2
[Transformer TF300T General] aerdely:
Before you rma'd it was it unlocked
[Transformer TF300T General] pjc21:
It could be as aerdely said, that the asus system/server still have your device info as already unlocked if you unlocked prior to rma - not sure here.

Not sure if you tried this already but asus released the v8 unlock tool for the jb 4.2.1 update and I have read that it does work for some on 4.1.1 but as it not working and your now back on 4.1.1 I would try the v7 unlock tool for jb 4.1.1

I think there is a download link for v7 somewhere in the threads - if not I think I still have a copy on pc - let me know
[Transformer TF300T General] aerdely:
In some cases such as on my original tablet before exchanged for new one i updated to 4.2.1 right away and at that point not knowing they were going to release the v8 tool i ran the v7 on 4.2.1 and worked for me now that i'm back with a warranty and want to stay there for the time being or till it runs out not making that mistake again. Point being in some cases can use either tool although it said was unlocked in upper left corner of screen and lost updates i assumed it worked but don't own a pc so couldnt attempt to flash recovery which i dont think twrp 2.4.4.0 was even out either so good thing.

Like he said should use v7 unlock tool now that on 4.1.1 dont think you had exactly mentioned you were unlocked before rma'd but probably the case.

Some place in the threads some one had mention that they went through same thing with asus rma'd multipule times trying to get them to unlock it but as they said they can't unlock it for them and argued couple times which asus basically said he's SOL and won't fix it. Cost him some money for the rma's with no result.
[Transformer TF300T General] TPXX:
Quick info help

I have rooted and flashed roms on my phone several times, but in researching my tf300t it seems things are much more complicated. My basic question at this point is: I have a tf300t which came with ICS installed. Purchased it in May 2012 so it is an early version. It has been ota updated to the most current Asus stock rom. I have not done anything to this yet. Can I downgrade (as shown in earlier post) to 10.4.2.20 and get the ICS boot loader back and use nvflash?
[Transformer TF300T General] Kaptinkrunk:
It wasn't unlocked but when I rma'd it I told them I was going to unlock it but now I can't no matter what I try :/

Sent from my Galaxy Nexus using Xparent Cyan Tapatalk 2
[Transformer TF300T General] pjc21:
No unfortunately once you have updated to a jb bootloader there is currently no way to go back to an ics bootloader.

My tab came with jb 4.1 preloaded so I tried to go back to ics to obtain nvflash but have not found any way of doing this.

You should have no issues downgrading to 10.4.2.20 if you want as this is jb firmware (4.1).

The last ics firmware was 9.4.3.30 (4.0.3)
[Transformer TF300T General] TPXX:
Ok, thanks for the reply, but I'm trying to figure out the advantage of downgrading then? Whats the benefit?
[Transformer TF300T General] f69m:
When you downgrade from BL 4.2 to 4.1, you currently have a much bigger selection of custom ROMs to choose from. If your preferred ROM (including stock) supports the 4.2 boot loader, I can see no reason to downgrade.
[Transformer TF300T General] aerdely:
Unfortunately at this point no. Once you unlock the first time it goes in asus system like said and as there is no way back but to have asus replace your mainboard or something you still remain in there system as unlocked and for some reason they won't help with that as i mentioned with that other guy. He nor you can't do anything unless a new method of unlocking comes about but doesn't seem like any one is working on it since we already have the tool from asus. Sorry can't help at this point the best thing you can do is stay tuned to the threads and hope something else comes up. The only other thing at this point is root with motochopper method but still with no unlocked bootloader you can't do custom recovery and roms only allows you to use root required apps.
[Transformer TF300T General] TPXX:
Thanks you! That sums it up nicely.
[Transformer TF300T General] darhend30:
help?

i have followed this method of downgrading when i go to flash recovery i keep getting

sending 'recovery' <7500kb>...

FAILED (command write faild (no such device or address))

finished. total time: 0007s

dont know what to do any help?
[Transformer TF300T General] pjc21:
When you run command "fastboot devices" do you see your device s/n listed?
[Transformer TF300T General] darhend30:
Ye. But I'm not long having this problem it magically worked for me this morning but thanks
[Transformer TF300T General] Kaptinkrunk:
Its never been unlocked....

Sent from my Galaxy Nexus using Xparent Cyan Tapatalk 2
[Transformer TF300T General] aerdely:
Oh that you said it was. In that case it's a mystery not sure why it wouldn't unlock but your not the only one some people have reported not being able to unlock even though never unlocked before. Like you said could have something to do with the rma but doubt asus would purposly have done it maybe the new board or something who knows no way to tell. Like we said you can try using either asus unlock too if neither work then still pretty much stuck for the time being but some one is working on a fix for that. Heres a link on people working on fix yhey are asking for everyone with this particular issue to give them some info on whats happening, give thread a good read through.

http://xdaforums.com/showthread.php?t=2242020
[Transformer TF300T General] f69m:
Hmpf, I think I understand, what you say, but using some punctuation, some capital letters (where appropriate) and maybe some new lines for paragraphs would make your post much easier to read and to understand.

Sorry, couldn't resist! ;)
[Transformer TF300T General] aerdely:
Yea i read through that again. Saw where that could be confusing. Fixed it