Install OctOS Android 7.1.2 Nougat ROM On T-Mobile Galaxy S3 SGH-T999

Here is how to install OctOS Android 7.1.2 Nougat ROM on T-Mobile Galaxy S3 SGH-T999. T-Mobile Galaxy S3 SGH-T999 can be updated to the latest Android 7.1.2 Nougat OS via bloatware free OctOS custom ROM. Team OctOS has recently built the latest custom firmware for T-Mobile Galaxy S3 SGH-T999 which is based on Android 7.1.2 Nougat.

Samsung Galaxy S3 was the most successful releases, so developers build the Custom ROM and always try to tweak their releases for this device. We all know that Galaxy S3 will not receive the Android Nougat official update from Samsung but all thanks to the OctOS team to build the latest custom ROM and provide the Android 7.1.2 Nougat experience on T-Mobile Galaxy S3.

This custom ROM contains all features for which OctOS is known for, plus there are a couple of more Android 7.1.2 exclusive features like multi-window, multitasking, better notification management, Pixel Launcher, Kernel Adiutor-Mod, SuperSU, Power Menu and Status bar time and date options, Volume button playback control, more human emoji, improved security and much more.

Samsung has not officially announced this ROM but this is just a custom ROM so you may face some minor bugs and lags but do not worry about it. These bugs will be completely rectified in the final release. Your device must be rooted and installed with the latest recovery like TWRP or ClockwordMod (CWM) because OctOS custom ROM required a custom recovery to flash this ROM on T-Mobile Galaxy S3 SGH-T999.

By following this step by step guide, you can update your T-Mobile Galaxy S3 to Android 7.1.2 Nougat via OctOS custom ROM. This latest custom firmware brings all the official features, customizations, improvements and enhance your system stability. Before proceeding, don’t forget to take a full backup of all your valuable data. If you are interested in installing the OctOS Android 7.1.2 Nougat custom ROM on your T-Mobile Galaxy S3 SGH-T999 then go ahead and follow the given steps.

Install OctOS Android 7.1.2 Nougat ROM On T-Mobile Galaxy S3 SGH-T999

Android 7.1.2 OctOS Nougat Custom Firmware Features:

  • Substatum theme engine!
  • Tentacles settings!
  • Pixel Launcher
  • KernelAdiutor-Mod
  • SuperSU
  • Power menu options
  • Screenshot
  • Screen record
  • DPI settings
  • Status bar time and date options
  • Status bar network traffic indicator
  • Status bar notification settings
  • Quick tile settings
  • Many quick tiles including Tentacles and KernelAdiutor-Mod
  • Volume button playback control
  • Volume button wake


The OctOS Android 7.1.2 custom ROM and instructions given in this guide can be used only for the T-Mobile Galaxy S3. Check the model number of your Galaxy S3 from Settings > About Phone.


AndroidBlog will not be held responsible for any kind of damage occurred to your T-Mobile Galaxy S3 during or after the installation of OctOS Android 7.1.2 ROM. Proceed at your own risk SM- T999.


  • Create a proper backup of all your existing data and settings on the phone before moving on to the installation guide using a recommended custom recovery.
  • Enable USB Debugging Mode on the T-Mobile Galaxy S3 by navigating to Settings > Developer Options.
  • Verify that you’ve correctly installed the Galaxy S3 USB Drivers on the PC.
  • The Galaxy S3 should be rooted with the latest version of the custom recovery like CWM or TWRP installed.
  • The bootloader of your S3 must be unlocked.
  • Make sure that the battery level of the Galaxy S3 is at least above 80% before going ahead.

Required Files:

Steps to Install OctOS Android 7.1.2 Nougat Custom ROM on T-Mobile Galaxy S3:

Step No 1: – First, download OctOS Android 7.1.2 custom ROM for T-Mobile Galaxy S3  on the desktop of the PC.

Step No 2: – Plug your device to the PC using its USB data cable and mount its USB memory storage.

Step No 3: – Transfer OctOS Android 7.1.2 ROM .zip file which you’ve already downloaded from the above link to the root folder of your SD card on the phone.

Step No 4: – Unplug the Galaxy S3  from the PC and power it OFF to boot into Recovery Mode.

Step No 5: – Power ON the device while pressing and holding Volume Up + Home + Power buttons at the same time to enter into Recovery Mode.

Step No 6: – While your device is now in CWM Recovery, perform wipe data/factory reset, wipe cache partition and wipe dalvik cache also by navigating to Advanced > Wipe Dalvik Cache.

Note: – wipe dalvik cache will help you to prevent boot loops and other errors during ROM installation.

Step No 7: – Go back to the main Recovery Menu and choose install zip from SD card → choose zip from sd card.

Step No 8: – Navigate to the OctOS Android 7.1.2 custom ROM .zip file which you’ve already transferred to the SD card of your device previously. Select the ROM .zip file using the Power button and confirm the installation to begin.

9: – Navigate to +++++Go Back+++++ once the installation is completed. From Recovery Menu, reboot your device by selecting reboot system now.

Your Galaxy S3  will be reset and may take about 4 to 5 minutes to boot for the first time after installation.

Done! You’ve successfully updated T-Mobile Galaxy S3 to the latest OctOS Android 7.1.2 ROM.

Aamir Jamal

An Android Geek and audiophile who love to read and write reviews/tutorials about gadgets and new tech stuff. He has written 1007 guides and other posts.

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