Do you want the best ROM for your Galaxy S3? If so, then maybe the CM10 and AOKP based Thunderbolt Jelly Bean 4.2 software might be what you are looking for. The update had just been made available by those of xda-developers and during the present step by step guide we will be checking in how to install the same on your Samsung Galaxy S3 GT I9300. Therefore, now you have the perfect opportunity for updating the Galaxy S3 with the latest version of the Android system, the Jelly Bean 4.2 one, not to mention that features imported from the CM10 and AOKP ROMs will be flashed on your smartphone.

As stated, this firmware is being provided by those of xda-developers so we have them to thanks for this tutorial. Also, this means that the Android 4.2 software isn’t an official one therefore you must follow and complete a manual installation procedure that will take you through the flashing operation, so that in the end, the Galaxy S3 will be powered by the CM10 and AOKP based Thunderbolt OS. First, you will have to prepare the handset for the proper steps as this is being considered a risky method and you don’t want to brick your device while trying to update its operating system.

From what we could find out, this ROM is coming with the Android 4.1.2 platform and also includes some goodies from the CM10 and AOKP firmware, so your S3 will be installed with important features and capabilities. Furthermore, those who had tested the Thunderbolt software mentioned that the OS is a stable one, with no bugs or internal issues. Anyway, if you want to read more aspect related to this OS improvement, then I suggest you to go and check our source page, by using the link from here. If you do decide that this is what you need for your SGS3, then return here and begin by applying the next list of pre requisites. Shortly after that I will explain the update procedure, so let’s get started.

  • Backup the Galaxy S3 data because you will have to wipe the system, meaning that everything that is saved on the internal storage memory of your handset will be erased.
  • You can start by saving the contacts, messages and call logs. Then, you might want to backup the EFS.
  • For other backup tips and guides check our previous how to posts.
  • Then, you are dealing with a custom ROM, so this is a beta Android Jelly Bean 4.1.2 update. Therefore, for being able to install the software on your SGS3 you will first have to root your smartphone. Also, you can use one of our root guides.
  • The warranty will get void, so try not to mess things up. You can restore the warranty but only by updating with an official firmware released by Samsung, or by downgrading your S3 to the stock ROM. Then, the bootloader will be relocked and the root access revoked.
  • Next, get and install a custom recovery image for your phone. This is a complex tool that will be used later, for the update operation. You have more details about the same during the proper steps from below.
  • Now, make sure you can access a computer, use the USB cord and of course your phone should be near you.
  • On both, S3 and PC uninstall, or just deactivate the internet settings before starting the operation because these tools are usually interrupting the update procedure.
  • Check the battery status of your Galaxy S3. If there is less than 50% power left go and charge it. The CM10 and AOKP Jelly Bean software will be stopped otherwise.
  • On your handset, enable the USB debugging option.
  • Be aware that you should install and apply this tutorial only for the Samsung Galaxy S3 model number GT I9300 and not for similar smartphones because you can end up in bricking your Android powered devices.

How to Update Galaxy S3 with CM10 and AOKP based Jelly Bean 4.2 Thunderbolt Custom ROM Firmware

  1. From this page you can download the update file.
  2. First, save the file on your computer.
  3. Then, connect the device with the PC by using the USB cable.
  4. Next, select the ROM from the computer and copy-paste it, or drag and drop, to the phone’s SD card.
  5. You can now disconnect the S3 from the computer; you will no longer have to use the PC.
  6. Turn off the SGS3 and reboot in recovery.
  7. You can succeed with that by pressing and holding the Volume Up button, the Home key and the Power button at the same time.
  8. Once the recovery mode menu is being displayed you can start the update operation.
  9. Therefore, select “wipe data factory reset” and “wipe cache partition”. Remember to backup your S3 first, or else you will lose your personal info.
  10. Select “+++go back+++” and return to the main menu.
  11. Form there now select “install zip from sd card” and “choose zip from sd card”.
  12. You can get and apply the ROM; just pick the downloaded file and start the flashing procedure.
  13. The installation process will take a couple of minutes; be patience and don’t press anything else.
  14. In the end, from the recovery menu select “+++go back+++” followed by “reboot system now”.

Finally, you are done. That was the how to procedure from which you could learn how to update the Samsung Galaxy S3 to Android 4.1.2 Jelly Bean by installing the CM10 and AOKP based Thunderbolt custom ROM firmware. The software should work perfectly on your device, but after testing the same, return here and by using the comments area from below, share you impressions and thought with us and with other users. Also, don’t forget to subscribe to us for enjoying the latest Android related news and the best guides from your smartphones and tablets.

YMG · 6 years ago

Signature verification failed....what should I do?

Sam Ahmad · 6 years ago

So the Thunderbolt ROM has been installed in my GT-I9300 for 12 hours now, and id like to say, it is AMAZING. though it has a few downs it has MANNY ups!

Downs- lost Samsung apps i loved, ( S memo, Chat on,) Samsung tweaks ( Swipe to call )

Chassis overheats after quite some time
doesnt connect to my own WiFi, so i have to use my neighbours o.o
ups- faster ui, more project butter goodness , games work faster, custom rom animations, brilliant screen, and less lag.
plus the UiI selection at start up ( JB LaUNCHER, TouchwizUX, Timescape UI, )
either ways, BRILLIANT!

jorgerdz · 6 years ago

I can´t finish the download. Is there a torrent for this file?
Thanks for this guide.

Droid Warrior · 6 years ago

Thanks bro.
Works great with me AOKP milestone 1 on S3.
With a few additional links of 4.2 apps.

JKiler1 · 6 years ago

Nice article, but I don't see any mention of WHY I would want to do this. What's the benefit of getting 4.2?

Andres · 6 years ago

Hello. After applying the Update Galaxy S3 with CM10 and AOKP based Jelly Bean 4.2 Thunderbolt Custom ROM in my Samsung S3 I can't detect the mobile network CLARO of Argentina. What can I do?

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