When the screen of Huawei Y6II LYO-L21 mobile goes black but is detected on PC, it is called "soft dead" condition. This means that the boot files have become corrupt. Bypassing secure boot through DA Auth File allows SP Tool to revive the device. The phone can be revived by reflashing preloader, lk, boot and recovery.
When a user in Huawei Y6II LYO-L21 mobile encounters Factory Reset Protection i.e. FRP and the mobile asks for Google account, then usually most of the software fails. In such a case DA Auth File opens a secret door which bypasses the security of the mobile. This file gives full permission to SP Flash Tool or other professional flashing tools to erase the FRP partition directly. Without this process the mobile remains inactive, and new account cannot be added. That is why DA file is no less than a treasure in the world of technicians.