How to Flash CM13 Android 6.0.1 on Samsung Galaxy S3 T999


Based on official Android 6.0.1 Marshmallow, an unofficial CM13 custom ROM is now available for Samsung Galaxy S3. Bringing all the usual CyanogenMod features, you can now update Galaxy S3 T999 to Android 6 Marshmallow.

update Galaxy S3 T999 to Android 6


Prerequisites to update Galaxy S3 T999 to Android 6 CM13:

  • Backup any important data from your Samsung Galaxy S3 SGH-T999 as a complete wipe will be required during the flashing process.
  • Enable USB debugging option on your device: Settings > Development Options > USB debugging.
  • Samsung Galaxy S3 T999 must be rooted, unlocked and installed with a recovery tool like TWRP or CWM.
  • Your device must be charged to at least 60% of power.

Note: this tutorial is focused on T-Mobile Samsung Galaxy S3 SGH-T999; please do not try this guide on other Android & Samsung devices. The unofficial ROM is still in ALPHA phase, so please beware that some features might not function at their best.

How to update Galaxy S3 T999 to CM13 Android 6.0.1:

Required files: download CyanogenMod 13 Android 6.0.1 custom firmware for Galaxy S3 and save it on your computer. Do not extract the contents.

  • Connect Galaxy S3 to your computer using a USB cable and copy the zip file to your phone’s SD card.
  • Disconnect the USB cord and power off your Galaxy S3.
  • Boot it into recovery mode by pressing and holding Volume Up + Home + Power buttons together.
  • Perform a Nandroid backup of your current OS: Backup > backup and restore on ClockworkMod recovery.
  • Wipe data task: from the CWM recovery menu, select wipe data / factory reset and confirm the process. Then go on to wipe cache partition and wipe dalvik cache.
  • From recovery menu, select install zip from sdcard, followed by choose zip from sdcard. Locate the CM13 Android 6.0.1 custom firmware and confirm the flashing process.
  • Return back to main recovery menu and reboot your T-Mobile Samsung Galaxy S3 into the new custom ROM. First boot may take a few long minutes.

How to restore: If you want to return to previous OS on your SGS3, boot into recovery, select backup and restore then restore your previous ROM by selecting it from the list.

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