Update Galaxy S3 I9300 with CM12 Android 5.0.2 Lollipop OS

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Samsung Galaxy S3 is ready to receive Android 5.0 Lollipop OS. Even though not in form of OTA, your Galaxy S3 I9300 can now be updated to latest Lollipop firmware as new Android 5.0.2 ROM has been made available for your phone. Thus, during the following guide you will learn how to install CM12 custom ROM on your SGS3.

CM 12 for Galaxy S3 is great; the Android 5.0.2 Lollipop firmware is available thanks to those of xda-developers who have released the firmware. Thus, you can anytime choose to download the software in order to manually update your Samsung Galaxy S3 to latest Lollipop built. The CM12 platform is stable and according to the users who have already flashed it, everything is working and running without problems.

Bottom line, this release of CM12 is stable and smoothly runs on the Samsung Galaxy S3 I9300. For being able to install this Android 5.0.2 Lollipop OS you will have to use a custom recovery image on your device. Therefore, your SGS3 must be installed with CWM or TWRP recovery – or with any other similar custom recovery image. The custom recovery will be used on the flashed process as CM 12 ROM comes in form of a .zip update file.

CM12 brings a custom version of Android 5.0.2 Lollipop OS to your Galaxy S3. So, you are not dealing with an official Android update. Furthermore, the firmware will come pre installed with various features that cannot be found on the default Android system along with a custom UI that is only based on stock Android Lollipop software.

Getting your Galaxy S3 to Android 5.0.2 Lollipop OS using CM 12 custom ROM will make you void the warranty of your smartphone. But, on the other hand, once CM12 will be flashed you will be able to improve and power up the performances of your Android phone. In a few words, your S3 will now run better and faster and you will no longer have to deal with in built apps, bloatware and other security and default restrictions.

You should save the current ROM that runs on your Galaxy S3 before updating to Android 5.0.2 Lollipop via CM12 custom ROM. Maybe the new firmware will not be on your taste and you will want to go back to stock. Well, usually this downgrade operation is completed via Odin. But, if you choose to make a Nandroid backup, you can complete the downgrade process easier and without following a dedicated tutorial.

Moreover, take care of a general backup process too. You see, during the flashing procedure from below, your personal data, info and account will be removed as a wipe will be applied. Thus, at this point completing a backup is not an option for you.

Your Galaxy S3 must be rooted as a custom ROM such as CM 12 can be applied only on unlocked devices. Moreover, on the update process a computer will be required while your phone and its USB cable will have to be there too. As usual, on your phone USB debugging must be checked – you can do it from “menu – settings – developer options” and on your computer any security protection deactivated.

This step by step guide must be completed only if you want to learn how to install CM12 based on Android 5.0.2 Lollipop OS on the Samsung Galaxy S3 model number I9300 – the steps from below will work only on the mentioned conditions so don’t mess thing up.

How to Update Galaxy S3 I9300 with CM12 Android 5.0.2 Lollipop OS

  1. Navigate towards this page and download the update file. Then, go here and download Google Apps package for your phone.
  2. Place both files on your computer – on desktop and don’t unzip anything.
  3. Connect your Galaxy S3 with your computer; plug in USB cable in that matter.
  4. Place the CM 12 file with Google Apps package on your phone’s SD card and in the end unplug the USB cord.
  5. Enter recovery mode on your Samsung Galaxy S3.
  6. From this point, choose the following options: “wipe data factory reset”, “wipe cache partition” and “wipe dalvick cache”.
  7. After that, choose “install zip from SD card” and “choose zip from SD card”.
  8. And in the end select the Android 5.0.2 Lollipop update and flash it on your phone. Of course, do the same thing with Google Apps package.
  9. Finally, from main menu of recovery select “reboot system now”.
  10. Done.
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Andy Stevenson

Andy is a senior editor here on Android Flagship and you can surely rely on its experience as the Android subject is more than a hobby to him. Andy is currently focusing on developing dedicated and detailed tutorials, tips and tricks, so you will be able to find its work through the “how to” section of our website. Also, don’t hesitate and contact Andy if you have questions or if you want to hear a second opinion about anything that’s related to the Android OS.