Why can the Redmi A5 not be unlocked after an OTA update?

Thank you for supporting Redmi products.
If the phone can’t be unlocked after an OTA update, please refer to the following details:
1. After an OTA update, the system requires around 15 minutes to complete the merging of the update package in the background;
2. During this critical process, if you enter fastboot mode in an attempt to unlock the phone, the system’s merged data will be erased or corrupted. This can lead to a verification failure of the mirror check header file, ultimately causing the device to crash or become unresponsive;
3. If this issue arises, the only way to restore the phone to normal operation is by flashing the firmware manually using fastboot mode.