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Update Galaxy S3 I9300 to Jelly Bean 4.1.2 with _miui.polimorph_ Custom ROM

Samsung Galaxy S3 is one of the most popular Android based smartphone available on the market, so the third party devs are working hardly to provide suitable updates for its users. But there are so many firmware released for the Galaxy S3 that is really hard to decide which software to choose as some are good for improving the performances, other for changing the looks, for adding apps and features and others are being designed to increase the speeds and upgrade the battery life. Well, today I will show you how to install the Jelly Bean 4.1.2 powered miui.polimorph custom ROM on your Galaxy S3 I9300, which is a platform that tries to combine almost all the aspects presented above.

The miui.polimorph update is being based on the CM10 and MIUI ROMs, so your handset will be installed with all the features that are being included in the mentioned firmware. Beside that you will also get extra capabilities that can be used for changing and optimizing the looks, the menu, for adding new capabilities, for improving the battery life and most important for receiving more speed from your SGS3. Furthermore, the Android 4.1.2 Jelly Bean OS will be flashed on your phone, though you will not be enjoying the default Android experience, as we are dealing with a custom ROM and not with an official update provided by Samsung.

Because of that, for installing the CM10 and MIUI based miui.polimorph ROM on your Galaxy S3 and update to custom Jelly Bean 4.1.2 software, you will have to use and apply this step by step guide which will show you how to manually flash the firmware and how to prepare the device for the installation procedure.

The guide is not hard to complete but you do have to read and perform everything that is mentioned during the next lines or else you can brick your S3 while trying to update its system. Now, if you need more info related to the miui.polimorph custom ROM, then you can go here and take a look over our source page. The firmware has been developed by those of xda-developers so we have them to thanks for the present tutorial.

Being a custom ROM, which means an unofficial update, the miui.polimorph OS will require access to the internal files of your Samsung Galaxy S3. So, you will have to root the Galaxy S3 first, or else you can’t complete this guide. By rooting the system you will remove the factory restrictions therefore the warranty will get void. Be careful in what you do and try not to mess thing up. Anyway, if you will need to you will be able to restore the lost warranty if you reset the flash counter. You can do this by downgrading the Galaxy S3 to stock Jelly Bean ROM, or to update with a future official update released by Samsung.

As soon as the system is rooted you can install complex and custom apps on your device. So, related to this guide, you need to flash a custom recovery image, like CWM recovery, on your SGS3. Without this tool you will not be able to apply the miui.polimorph Jelly Bean 4.1.2 ROM, so don’t skip this part. Now, let’s see which the general pre requisites are.

  • Backup the Galaxy S3 data because a full wipe of the system will be completed in order to install the present CM10 and MIUI based firmware.
  • Use this guide and learn how to save the messages, call logs, current ROM, contacts and this guide for learning how to backup EFS.
  • A Windows running computer or notebook is required and the smartphone and its USB cable should also be there.
  • On both computer and device you should deactivate or uninstall the security tools and options; these programs are interfering with the update procedure.
  • Check the battery status of your handset: if there is less than 60% power left you should charge the battery (or else the S3 might get turned off in the middle of the installation operation), else skip this step.
  • Enable the USB debugging option on your phone for being able to connect the device with the computer.
  • This guide is being suitable only with the Samsung Galaxy S3 model number I9300, so don’t apply the next steps for a similar handset as you can end up in bricking your Android powered smartphone.

How to Update Galaxy S3 I9300 to Jelly Bean 4.1.2 with _miui.polimorph_ Custom ROM Firmware

  1. Remember to root, install a custom recovery image and to backup the data from your Galaxy S3.
  2. Then, on your PC download the update file by using the link from here.
  3. Use the USB cable and connect your handset with the computer / notebook.
  4. Pick the downloaded file and copy-paste it to your phone’s SD card.
  5. Unplug the USB cable.
  6. Turn off the phone.
  7. Reboot into recovery mode: press and hold the Volume Up, Home, and Power buttons at the same time.
  8. From recovery select “Mounts and storage” followed by “Format /preload partition”.
  9. Also select “wipe data factory restriction”, “wipe cache partition” and “wipe dalvik cache”.
  10. Return to the previous menu by choosing “+++go back+++”.
  11. And then select “install zip from sd card” followed by “choose zip from sd card”.
  12. Pick the downloaded update file from the SD card and start the update process.
  13. When it is done, select “+++go back+++” followed by “reboot system now” and that’s it.

Congratulation, your Samsung Galaxy S3 has been installed with the miui.polimorph custom ROM firmware. Remember that this OS is being based on the CM10 and MIUI platforms and brings the Android 4.1.2 Jelly Bean software, so test it and make sure that everything is working as expected. Tell us what you think about this update and share your thoughts with us by using the comments are. Don’t forget to subscribe with us for receiving further tutorials, guides and Android related tricks, tips and latest news.

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