Update Galaxy S3 I9300 to Android 5.0 Lollipop via unofficial CyanogenMod 12 ROM
IBTimes UK

Owners of Galaxy S3 (GT-I9300) are in for some great news, as the industrious CyanogenMod team has unleashed its first unofficial CyanogenMod 12 (CM12) ROM based on the latest Android 5.0 Lollipop update for Samsung's former flagship phone.

As the CM12 ROM is still in its Alpha stage of development, its features are not completely tested and it may harbour a few untested bugs or broken features.

Nevertheless, those who want to get a first-hand experience of running Lollipop on their ageing Galaxy S3 can go ahead and install the CM12 ROM, using the step-by-step guide provided below.

IBTimes UK reminds readers it will not be held liable for any damage to device during or after Android 5.0 Lolliop firmware installation. Users are advised to proceed at their own risk.

Pre-requisites

  • The instructions given in this guide are meant for the international variant of Galaxy S3 with model number GT-I9300 only. Verify device model number by navigating to Settings > About Phone.
  • Ensure the phone has at at least 80% battery charge to prevent unexpected device shutdown (due to battery drain) while installing the ROM.
  • Back up data and settings using a recommended custom recovery tool, like ClockworkMod (CWM) or TWRP, as it creates a complete image of the existing phone setup. In Recovery, choose Backup and Restore and tap Backup.
  • Verify correct USB drivers for the phone are installed on the computer (download Galaxy S3 USB drivers).
  • Enable USB Debugging mode via Settings > Developer Options (if running Android 4.0 or above) or Settings > Applications > Development (if running Android 2.3 or earlier).
  • Ensure that the device is rooted with CWM recovery installed and its bootloader is unlocked.

Downloads Required

CyanogenMod 12 Android 5.0 ROM

Google Apps

Steps to Install Unofficial CyanogenMod 12 Android 5.0 ROM on Galaxy S3 I9300

Step 1 - Download CyanogenMod 12 Android 5.0 custom ROM for Galaxy S3 on the computer.

Step 2 - Connect and mount the phone's USB mass storage on computer with USB cable.

Step 3 - Now, copy the downloaded CM12 ROM zip file to the root folder on the phone's SD card.

Step 4 - Power off the phone and disconnect its USB cable from computer.

Step 5 - Now boot the device into Recovery Mode by pressing and holding Volume Up, Home and Power buttons together.

Step 6 - Once the phone enters into CWM Recovery, perform a full data wipe task by clicking Wipe Data/Factory Reset. Use the Volume keys to navigate between options and Power button to select an option in the Recovery Mode.

Step 7 - Then, perform Wipe Cache Partition and wait until the process completes.

Step 8 - Now perform Wipe Dalvik Cache as well. To do this, go to 'advanced' option and then click Wipe Dalvik Cache. This will help in preventing boot loop issues or any boot ROM related errors during firmware installation.

Step 9 - Then return to the main recovery menu and choose Install Zip fromSD card.

Step 10 - Now click Choose Zip from SD card. Use volume keys to navigate to the CM12 ROM zip file that you copied earlier to your phone's SD card and choose it by tapping the Power button. Confirm the ROM installation on next screen and the installation process will begin.

Note: Repeat Step 9 and Step 10 to install Google Apps (Gapps) as well.

Step 11 - Once the ROM and Gapps installation completes, go to "+++++Go Back+++++" and select Reboot System Now in the Recovery menu.

The phone will now reboot and the first boot may take about five minutes to complete. So, please be patient.

Your Galaxy S3 I9300 is now running the latest Android 5.0 Lollipop via CM12 custom ROM. Go to Settings > About phone to verify the firmware version installed.

[Source: Team Android]