Press and hold the buttons simultaneously for 5–8 seconds until the update screen appears. Normal Upgrade (If the phone is working) : Insert the SD card and go to Settings > System Update . Select Local Update to begin the process.
The most critical step is sourcing the correct firmware. Huawei firmware files usually come in a compressed format (ZIP or RAR). huawei cun-l21 flash file sd card
You might need to flash your device if you are experiencing: Press and hold the buttons simultaneously for 5–8