Samsung Galaxy S3
Samsung Galaxy S3Wikicommons/Vinith Devdas

Prolific custom ROM developer community CyanogenMod has released the new CM13 series firmware to Samsung's 2012 flagship smartphone Galaxy S3.

The new CM13 custom ROM is based on the latest Android Marshmallow OS. It is around 260MB in size and brings Doze battery saving feature, new security boot feature and other value-added features enhancing performance and user-experience on Galaxy S3.

Read more: Google Android 6.0 Marshmallow: 7 key features you need to know

Prerequisites (things to remember before installing Custom ROM):

  • This new CyanogenMod CM13 Android 6.0 Marshmallow custom ROM has to be installed on the Samsung Galaxy S3 (GT-I9300) 3G model with Exynos chipset only, if tried on other devices, it might get bricked [to check your device model: Go to Settings >> About phone >> model number]
  • Though installing custom ROM improves the device's performance and UI experiences, it makes the company warranty void; the company will no longer be liable to provide updates in future [users can restore warranty by flashing the device with stock-ROM].
  • Make sure the device is rooted before going ahead with custom ROM installation.
  • Installation of custom ROM requires clearing memory in the tablet, so make sure to back all the data by installing Clockwork Mod (CWM) Recovery/ TWRP in the smartphone.
  • Make sure USB driver is installed in the PC or else your device (Galaxy S3) will not be recognised by the computer.
  • [Disclaimer: This procedure is very technical and should be performed by a person with sound knowledge of rooting (or manual software installation) Android devices. If the step-by-step installation process is not followed properly, there are chances of the smartphone getting bricked or being permanently irreparable. IBTimes India cannot be held responsible for any damage or claims from readers if the procedure does not yield the required results or if the smartphone is bricked. Hence, users are advised to proceed with caution.]

Tutorial: Step-by-step installation procedure of CyanogenMod CM13 Android 6.0 Marshmallow custom ROM on Samsung Galaxy S3 (GT-I9300) -

Step 1: After downloading CyanogenMod CM13 Android 6.0 Marshmallow custom ROM and Google Apps on to your PC, connect Samsung Galaxy S3 I9300 to PC via USB chord.

[Note: Scroll down to find the downloadable files]

Step 2: Place Android Marshmallow zip file and Google Apps .zip file into the phone's SD card memory. [Note: Users are advised to paste the .zip file in SD card root, not in any other folder.]

[Note: Before installing the custom software, be sure that the device must have been rooted and has installed ClockworkMod Recovery tool.]

Step 3: Turn off the device and disconnect from the PC.

Step 4: Perform the regular Recovery Mode sortie by press holding 'Volume (up)', 'Home' and 'Power' buttons.

Step 5: After entering the RECOVERY mode, clear the phone memory, by choosing 'wipe data/factory reset' option.

[Note: use 'Volume' keys to navigate and 'Power' button to select options, while operating under Recovery Mode]

Step 6: Clear the cache memory by selecting 'wipe cache partition'

Step 7: Go back to ClockworkMod recovery, and select 'advanced' and tap 'wipe dalvik cache' [Note: This step is optional, but many recommend this procedure so that user will not face boot loops or any other errors in the middle of custom ROM installation]

Step 8: Return to the main recovery screen and then tap 'install zip from SD card'

Step 9: Tap 'choose zip from sdcard' and go to Android Marshmallow ROM .zip file in SD card and enter the installation process. Repeat the same procedure to install Google Apps [Note: use 'Volume' keys to navigate and 'Power' button to select options]

Step 10: Once done with the installation process, navigate to '+++++Go Back+++++' and re-start the device by opting 'reboot system now' seen in the recovery menu.

Now, your device (Samsung Galaxy S3 I9300) will take a minimum of five minutes to complete the booting process.

Users then head to Settings >> select 'About phone' to confirm the installation of CyanogenMod CM13 Android 6.0 Marshmallow custom ROM.

Downloadable files:

CyanogenMod CM13 Android 6.0 Marshmallow custom ROM for Galaxy S3 (GT-I9300): HERE

Cyanogen Recovery: HERE

Google Apps: HERE

USB driver: HERE