Unable to update Galaxy S3 Android after flashing CWM I just unboxed a Samsung Galaxy S3 and immediately, before first boot, rooted it installing CWM Recovery and SuperSU. I found it to be not the best idea, becuase I forgot to launch the Samsung update to 4.1.

In fact, stock upgrade does reboot the phone into recovery but then CWM says the signature is invalid, etc. I should have done all this in inverse order (first stock upgrade, then root).

The question is: how can I upgrade this Galaxy to stock JB?

Idea: restoring the original recovery... but how?
This thread gives a nice step by step tutorial on how to re-flash to stock ICS, which will relash the stock recovery.

In a nutshell:


  How to restore Galaxy S3 to Android 4.0.4 ICS XXLAF2 stock firmware:
  
  
  Download the ICS stock firmware file from here
  or here.
  After the ROM file is downloaded successfully, you should extract its contents and you will get a single file with the ‘.tar.md5′
  extension. Save it on your computer’s desktop.
  Download Odin3 3.o4 for Galaxy S3 I9300 from here.
  Extract Odin.zip contents into a single folder and save it on your PC desktop.
  Now, power OFF your Galaxy S3 phone and after this you will need to boot into download mode.
  Boot into download mode by pressing ‘volume down’ + ‘home’ + ‘Power’ and release these buttons only after the display powers ON.
  Press Volume Up button to confirm that you want to load download mode.
  Now, go to your PC and launch the ‘Odin’ executable file. The one you’ve extracted at step 4.
  Next, connect your SGS3 I9300 to your computer and ODIN should display a message box saying ‘added!!’. If you don’t see this message
  then it means that the USB drivers aren’t installed on your PC and you
  should use the download links in the preparation guide, the ones
  listed above this tutorial guide. If Odin did find the Samsung USB
  Driver you’re free to move to the next step.
  In Odin click the button that is called ‘PDA’.
  Find the file you’ve extracted at step 2. It should have the ‘.tar.md5′ extension. Select it and it will be loaded into Odin. NOTE:
  Don’t change any of the Odin’s default settings and make sure that the
  ‘re-partition’ option isn’t selected.
  Press the START button in ODIN and the program will now begin to install the stock firmware files. When the installation is complete
  you will see a ‘PASS’ alert displayed by Odin and this means that
  everything went according to plan. Your phone will also restart and
  after the Samsung Logo appears you are free to unplug the device from
  your computer. NOTE: If Odin gets stuck you are required to disconnect
  the phone from your PC and remove its battery and then re-insert it
  and, now repeat all the entire tutorial once again as something went
  wrong and the firmware wasn’t flashed.
  That should do it, now your phone has been restored to factory stock firmware. Make sure to use the comments section in case you
  other questions.