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

This guide installs /e/OS on your sapphire. Read it through once before you start, so you don’t hit surprises partway in. Downgrading from a newer OS version than the /e/OS build you’re about to install can cause instability or brick some devices — check your current OS version first. Flashing is done at your own risk: /e/OS builds are provided as best effort, without any guarantee, and the /e/OS project takes no responsibility for the consequences.

Requirements

  • Back up your important data to an external storage device — some of the steps below format the phone, wiping any backup left on it.
  • Charge your phone above 50%.
  • Enable adb and fastboot on your PC — setup instructions.
  • Download every file listed in the Downloads section below before you start.
  • Use a real data cable — some cables only charge and can’t transfer data.
  • Enable USB debugging on your device — instructions.
  • Confirm your exact model in the Device Selector: where shown, hover the device name for the supported model number, and check it matches yours exactly.
  • Boot the stock OS at least once and check everything works — SMS, calls, and both over WiFi and LTE if available (some devices need VoLTE/VoWiFi used once on stock to provision IMS). Whatever’s broken on stock stays broken on /e/OS.
Warning: Log out of any accounts (Google, Samsung, Mi Account, etc.) set on the stock ROM before proceeding. Most vendors enable Factory Reset Protection (FRP): after a factory reset, a device that's still signed in will ask for the credentials of that account before it can be used again. Also remove any screen locks.
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

official /e/OS A16

Not sure which one to pick? See official vs. community builds.

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
  • 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

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