Huawei Y5 II CUN-L21 Mobiles face issues like region lock or operator lock where the phone works on a specific network. To remove such restrictions, the use of DA Auth File becomes necessary, as it takes the partition from read-only to write mode. This allows you to manually edit specific configurations such as modem config or carrier policy files. It is the skill of an experienced repairing engineer to find a way to unlock from the DA file.
When Huawei Y5 II CUN-L21 mobile does not exit fastboot mode even after flashing firmware, then assume that the boot partition or recovery partition is corrupted. To fix them, provide the DA Auth File with SP Tool so that those partitions can be re-flashed. This is the only way to achieve fast recovery in encrypted or secure boot enabled devices.