| Error | Cause | Solution | | :--- | :--- | :--- | | (Incompatibility) | Wrong firmware version or hardware mismatch. | Download the specific firmware for your phone's region (e.g., C10 for Russia, C636 for Asia). | | No DLOAD screen (Phone just boots normally) | SD card not formatted to FAT32 or folder name is wrong. | Reformat the SD card to FAT32 (Default allocation size). Ensure folder is dload (not Dload or DLOAD). | | Update stops at 5% | Corrupted UPDATE.APP file. | Re-download the firmware file. Do not use a slow/unstable internet connection. | | Phone stuck in "Emergency Download mode" | The bootloader is severely damaged. | You must now use the PC-based SP Flash Tool (for MediaTek) or Research Download Tool (for Spreadtrum). |
Do not attempt to downgrade from Android 6.0 (if you previously updated) to Android 5.1 using this method. Downgrading without a full factory wipe often causes IMEI (Network) loss. huawei cun-l21 flash file sd card