The process may take 5–10 minutes. The phone will reboot once finished. Alternative: Using PC Flash Tools
If you already have a .zip or .rar file asking for a password, try these common passwords used by uploaders:
This guide is for educational purposes only. Flashing your device may void your warranty. Ensure you have the legal right to modify your device. The author is not responsible for any data loss or hardware damage.
If you followed this guide correctly, your Huawei TRT-L21A should now be booting up, lock-screen free, ready for a fresh start.