Perform a "Wipe Data/Factory Reset" from the Recovery Menu (Volume Up + Power) after the flash is complete.
Before proceeding, ensure you have completed the following steps to avoid damaging your device: huawei-ascend-g620s-l01-stock-firmware-rom-flash-file
Ensure your battery is charged to at least 50-60% to prevent the device from shutting down during the process. Perform a "Wipe Data/Factory Reset" from the Recovery