Install /e/OS on a Teracube Teracube 2s (2025) - “sapphire”

The instructions in this guide will assist you to install /e/OS on your sapphire. Please read through the instructions at least once before actually following them, so as to avoid any problems later.

It is important that you know that downgrading Smartphones on OS versions greater than the /e/OS OS version you plan to install, can cause instability or at worst brick some devices. We recommend that you check your current OS version, before attempting the installation.

It is advisable to flash your device only if you know what you are doing and are ok taking the associated risk. All /e/OS builds are provided as best effort, without any guarantee. The /e/OS project and its project members deny any and all responsibility about the consequences of using /e/OS software and or /e/OS services.

Requirements

  • If required take a backup of all important data from your phone on an external storage device before proceeding.
  • Do not take a backup on the same device as some of these actions will format the device and delete the backup.
  • Ensure your phone is charged more than 50%
  • Check that adb and fastboot are enabled on your PC. If not you can find the setup instructions here
  • Download all the files and images mentioned in the download section below before starting the installation

  • Make sure you have a working data cable to connect your device to the PC. There are cables which are only for charging and do not transfer data.

  • Enable USB debugging on your device. You can find the instructions here
  • Make sure that your model is listed in the Smartphone Selector. Check the model supported. Where available, information on the model supported should show as a pop-up when you hover the cursor on the Device name. The model number supported should be the exact same.
  • Boot your device with the stock OS at least once and check every functionality.
Warning: Make sure that you can send and receive SMS and place and receive calls (also via WiFi and LTE, if available), otherwise it will not work on /e/OS as well. Additionally, some devices require that VoLTE/VoWiFi be utilized once on stock to provision IMS.

Please share your experience , suggest tips or changes to this install guide documentation by visiting the Teracube 2s (2025) specific topic on our community forum.

To report issues in /e/OS please refer this guide

Caution: Before moving forward, ensure your device is a Teracube 2s (2025). Please look at the serial number under the battery or dial *#06#. If the serial number starts with 2025 (ex: 202501T2Sxxxxxx), you are at the right place!

Downloads for sapphire

To understand the difference between /e/OS builds check this guide

Warning: Please note some of the above links can lead to external sites

Enabling USB debugging and OEM unlock

Caution: Please take a backup of your data as unlocking the bootloader will reset your device to factory defaults.
  1. Connect device to a PC via USB-C cable
  2. Enable Developer Options following the guide given here
  3. Enable USB debugging option following the guide given here
    • Click on OK for Allow USB debugging? prompt
    • Click on Allow for Allow USB debugging? prompt showing computer’s RSA key fingerprint
  4. Enable OEM Unlock option following the guide given here

Booting into fastboot and unlocking bootloader

  1. Reboot to fastboot using either of two methods (Automatic or Manual)
    • Automatic
      • From your computer, run adb reboot bootloader
    • Manual
      • Turn off your phone and enter boot menu by holding volume up and power keys
      • The boot menu will present three options, press volume up until Bootloader is selected
      • Press power to accept this choice
  2. Unlock the device with the following command
    • fastboot flashing unlock
  3. Accept any prompts that may appear on device
  4. If successful, it will show success message on PC and device
  5. Reboot the device with the following command
    • fastboot reboot

Installing /e/OS from the bootloader

Tip: For Windows users, we advise to use Git Bash. For more info about Downloads and Installation see Official Documentation
  1. Unzip the archive 
     unzip <fileyoudownloaded>

    Replace <fileyoudownloaded> with the name of the archive file you downloaded Alternately, you can create a folder and unzip the archive there

  2. Confirm that extracted directory contains following content:
    • bin-linux-x86 directory - which contains linux tools including fastboot and adb
    • bin-msys directory - which contains Windows tools including fastboot and adb
    • bin-darwin directory - which contains MacOS tools including fastboot and adb
    • img files - The img files to be flashed on the device
    • flash_sapphire_factory.sh - The installer script
  3. Boot into bootloader/fastboot mode
    • Turn off your phone and enter boot menu by holding volume up and power keys
    • The boot menu will present three options, press volume up until Bootloader is selected
    • Press power to accept this choice
  4. Run the installer script on Terminal(Linux) or on Git Bash UI(Windows)
    • Make sure you are in the current directory which contains the flash_sapphire_factory.sh file Linux
    • Right click -> Open terminal here Windows
    • Right click -> Git Bash here
    • Execute the following command: 
      chmod +x flash_sapphire_factory.sh && ./flash_sapphire_factory.sh

      The script will flash all required files and reboot device automatically

Booting into fastboot and locking bootloader

  1. Reboot to fastboot using either of two methods (Automatic or Manual)
    • Automatic
      • From your computer, run adb reboot bootloader
    • Manual
      • Turn off your phone and enter boot menu by holding volume up and power keys
      • The boot menu will present three options, press volume up until Bootloader is selected
      • Press power to accept this choice
  2. Lock the device with the following command
    • fastboot flashing lock
  3. Accept any prompts that may appear on device
  4. If successful, it will show success message on PC and device
  5. Reboot the device with the following command
    • fastboot reboot
Success: Congratulations !! Your phone should now be booting into /e/OS !!
To find some troubleshooting tips… click here

adb

  • Getting a Total xFer ':' 0.01x message - Try to upload the /e/OS to internal storage and retry to install
  • adb ':' sideload connection failed ':' insufficient permissions for device error - Try to execute the commands adb kill-server and adb start-server and retry
  • Running adb shell twrp install /sdcard/</e/OS zip package> raise non-existent directory error - Try to check solution here
  • Getting an insufficient permissions error - Try the solution given here
  • When running "adb devices" in bash a device is shown as "unauthorized" - Try the solution given here

TWRP

  • Errors while running TWRP version 3.4.x.x or above - Try downloading and using a previous TWRP version.. below 3.4.x.x
  • In TWRP if this error shows up failed to mount /preload - Try in TWRP wipe screen in advanced menu select preload and swipe to wipe
  • /cache/recovery/xxx -> no such file or directory error while flashing a ROM - On PC run adb shell in the console now create a folder called recovery for e.g. here the devicecode name is violet "violet :/cache# mkdir recovery"

Connectivity

  • Trying to troubleshoot mobile connectivity issues - Read this guide



Please share your experience , suggest tips or changes to this install guide documentation by visiting the Teracube 2s (2025) specific topic on our community forum.

To report issues in /e/OS please refer this guide