How to Fix "Failed (remote: ‘unknown cmd’) fastboot: error: Command failed" on Tecno Devices

Will This Step-by-Step Guide Solve the Fastboot Command Failed Error on Tecno Devices? Is Your Tecno Showing 'Unknown cmd' in Fastboot? Here’s the Proven Unlock Fix

Tecno devices often trigger the “Failed (remote: ‘unknown cmd’) fastboot: error: Command failed” message when attempting to unlock the bootloader with standard fastboot commands. This error is especially common on models with MediaTek chipsets, where the generic fastboot flashing unlock command is unsupported.

Why This Error Occurs

Tecno devices, particularly those with MediaTek chipsets, do not support the standard fastboot unlock command used on many other Android brands. The device’s bootloader requires a signed identifier token and a special unlock sequence, which cannot be bypassed with generic commands.

Step-by-Step Solution

1. Boot into a Linux-based OS (Ubuntu Live USB or a Linux VM on Windows) for compatibility with required tools.
2. Install MediaTek USB drivers on your PC.
3. Download and extract Android SDK Platform Tools.
4. Download and extract the modified_fastboot ZIP, which provides custom fastboot binaries and scripts for Tecno devices.
5. Enable USB Debugging and OEM Unlocking in Developer Options.
6. Connect your Tecno device to the PC with a reliable USB cable.
7. Open a terminal in the platform-tools directory.
8. Enter the following command to boot to Fastboot Mode:

   ./adb reboot bootloader

9. If this fails, manually boot to recovery and select Fastboot Mode from there.
10. Run the following command to verify device connection:

    ./fastboot devices

11. If your device isn’t detected, install the correct fastboot drivers.
12. In the modified_fastboot folder, run the following command to obtain identifier token:

    ./fastboot oem get_identifier_token

13. Copy the output token.
14. Run the following command to sign the identifier token:

    ./signidentifier_unlockbootloader.sh [YOUR_IDENTIFIER_TOKEN] rsa4096_vbmeta.pem signature.bin

15. This generates a signature.bin file needed for unlocking.
16. Execute the following command to unlock bootloader:

    ./fastboot flashing unlock_bootloader signature.bin

17. Confirm the unlock on your device using the volume keys when prompted.
18. Once the process completes, reboot with:

    fastboot reboot

Troubleshooting Tips

• If you see “unknown cmd” or the device isn’t detected, double-check drivers and use a different USB port or cable.
• Ensure you’re using the modified fastboot binary, not the standard one from Android SDK.