I'm in the middle of rooting my S3 following this guide.

I've followed the instructions and used Odin but now my S3 is stuck in the boot screen (ie the black one that says Galaxy SIII GT-19300).

Anyone have any advice to get it working?

Take the battery out for 30 seconds and try again. Bear in mind the first boot after flashing may take a while. If that fails, can you get into the recovery console with the usual button combination on powering the phone up? If you can get to that menu, it may be worth first trying a data wipe again (I assume you'll restore apps and data once the phone is back up and running). Wipe Data Partition and Wipe Dalvik Cache from the recovery menu and try again.

Never fear, you'll have to go some to brick a modern smartphone.

Yes I can get in to the recovery console, when I do a data wipe I get a list of data at the bottom but one of them says 'Error mounting /data" although the final one says 'Data wipe complete' but when I then select 'reboot system now' it restarts but stays on the boot screen again.

Try rerooting your phone you should be able to get it back.

Have a read of this thread.

Cheers so far guys - I'm not able to re-root as I need to enable USB debugging and it appears to be off (the software I use first of all is now just hanging there waiting for it to be activated so I assume it's off) so for now I'm following this guide http://reviews.cnet.co.uk/mobile-pho...y-s3-50009490/ and I'll see how it goes.

From what I can tell if I'm able to get to the recovery screen then the chances are all is not lost...yet...

From that link - DO NOT USE ROOT66 OR THE LINKED BOOT CHAINS IF YOU ARE ON ANOTHER CARRIER! YOU MUST USE YOUR OWN DEVICE-SPECIFIC FILES!

How do I find the correct files? It's a non-branded non-LTE handset.

Did you do the data wipes from the recovery? The previous link may save you if all else fails but you need to find the correct files for your device e.g. a generic ROM. I don't think you need to resort to that method just yet but it's an option you may have to think about later.

As you say, getting to recovery means all is definitely not lost. It should mean you can re-flash a custom ROM/unlocked stock ROM of your choice from Odin at worst.

If it were me, I'd flash a generic ROM such as cyanogenmod (if you don't mind losing Touchwiz) but you can find stock firmware here I think, plus guides.

EDIT: I've always rooted my Galaxy S using CF-Root, which'll also give you the CWM Recovery. From that, you can flash cyanogenmod 10.2/11 if you want to go down that route.

Guide to flashing CF-Root on S3 for future reference if needed is here.

I'd first get a stock firmware flashed back on via Odin and regroup, though (if the data wipe didn't work).

Cheers for that - yes I did the wipe from the recovery screen.

I've just completed that cnet.co.uk guide and it seems to have worked! Thanks for all the info

Excellent news! Hope you enjoy your rooted S3 (Titanium Backup and Adfree (available from here) are must-haves IMHO).

OK this is strange - it is now rooted but the Samsung shizzit is still on it and the software has rolled back - I was on 4.1 but it's now 4.2.

Rooting only adds software, it doesn't remove anything.

If you used that CNET guide, it would have flashed whichever firmware you downloaded. There are stock firmware, so will have all the Samsung stuff. If you don't want this,you need to flash a custom ROM like Cyanogenmod. Rooting just allows you to grant superuser privileges to apps and to modify system files.

To check if you are rooted, use the Root Checker app.

Yes I tried the root checker and now I'm no longer rooted. FFS...

I half expected that - you essentially recovered your phone by re-flashing official firmware, so you would lose root even if the aborted attempt had partially worked.

What I'd suggest is you start again with the rooting process but this time use the CF-Root method I linked earlier, as this is a very common method by a renowned developer. This will also give the CWM recovery menu which you can then subsequently use to flash a custom ROM if you want to ditch the Samsung stuff or want a more tweakable ROM.

Alternatively, once rooted, you can simply uninstall the Samsuing apps you don't want using something like Titanium Backup Root and switch to another launcher if you don't want Touchwiz.

Watch a few YouTube videos on rooting the S3 with CF-Root to get familiar with the procedure - I'm sure there will be several (can't check as I'm at work).

First step is to get rooted successfully - you can sort the OS out once that's done and verfied to have worked.

Ok while I've been away I've successfully rooted it and am happily back on 4.1.2.

I'd rather get rid of anything Samsung-esque on it and just use straightforward Android software - is there an idiot-proof method?

https://play.google.com/store/apps/d...oneclick&hl=en

Install the app and it roots your phone and installs a version of the Android Open Source Project called CyanogenMod 10.2. Should work for the S3 (i9300 / i9305).

I tried that this morning - when I installed it on my pc it went through the motions of installing etc and then..nothing.

edit: and as I tried it for the 4th time it seems to be working....

*bangs head on wall*

Now for some reason the new OS won't recognise my memory card. I've pretty much decided I just want to go back to the original 4.1.2 but can I do that? I've tried the Galaxy S3 toolkit software but it just hangs on 'waiting for usb debugging' but I've already allowed that.

Is there anything on the memory card?

It is probably a formatting issue. I believe Samsung format it using exFAT, but AOSP/CM uses FAT32. Put it in an SD adaptor and hook it up to a computer to check the data is still on it. If it is then copy it to the PC, format the SD card back to FAT32 then copy the data back. Bit of a faff, but it should work.

With regards to going back to stock Samsung Android (AKA Touchwiz), it might be worth reading the XDA forums for the S3:

http://forum.xda-developers.com/galaxy-s3

There will be tutorial threads on there for returning to stock.

I have never gone straight from non rooted to custom rom.

Its better to first install cf-root kernel, which will root your existing rom, all data stays intact, settings, contacts etc.

Then install something likw CWM recovery, at this point you will then probably never need to use odin again unless you really mess up.

After CWM installed do whats known as a nandroid backup, this is basically a full backup of the rom on your phone, including kernel, modem, data etc. Whats not backed up is whats on the internal and external sdcard storage (reason is that stays intact in between wipes etc.).

At this point only then I would consider putting on a custom rom. As you now have a backup you can restore back to the shipped rom on the phone.

Be aware most custom roms I have used if not all of them are buggy, some bugs may be tolerable others may be severe. If you want a unbuggy root then just use cf-root on existing rom.

AOSP based roms like cyanogenmod tend to be very fast but also things like the camera tend to crash and the battery life gets very bad compared to touchwiz.

Omnirom has my eye currently, but its still been developed.

eg. currently I am diagnosing 5GHZ wireless issues which Qas* is aware of, I am likely to do a nandroid backup soon and restore my shipped rom to diagnose if thats an issue with the software setup or not. I am actually considering going back to my shipped rom permanently and just having that rooted since so many custom roms the dev's will say things like "tweaked" "optimised" without stating what they have specifically done and these tweaks may be causing other issues.

Some other things to be aware off.

Android 4.2+ the storage paths changed to support multi user, if you go from android 4.1 or older to 4.2+ the OS should auto handle the change, but if you then downgrade again you will need to manually fix the paths.

The newest modem drivers change the EFS layout, meaning unless you backup the old modem, once you have upgraded you cannot downgrade again. Dont assume you wont want to downgrade because there is many instances of people trying new roms and not liking them so going back, even the official 4.3 S3 rom is a mess to the point theregister did a news story on it.

OK I'm following this guide http://forum.xda-developers.com/show....php?t=2323847

I'm at Part 3, Device Wipe.

My phone is now stuck on the screen with the droid looking to the side and there's like a spinning 3-d star on his chest, it's been like that for about 5-10 minutes - does that sound right?

It restarted ok but I decided to just leave it on cyanogenmod even though I hate it.

I worked out that the memory card issue wasn't that it couldn't read it but for some reason it's not picking up the ringtones, saying they're the wrong file-type. I have them as WMA and MP3 but the phone still won't use them - which audio files does cyanogenmod recognise?