Paid professional software that can re-write the factory firmware (OFA/Scatter files) to reset the bootloader state.
The persist partition stores unique device identifiers. If you have previously flashed a stock ROM incorrectly, rooted your phone, or used a tool that wiped the persist.img , your phone might actually broadcast a null or wrong serial number during Fastboot mode. In this case, even an official token will fail. the serial is not match fastboot unlock verify fail oppo
If you are stuck in this loop or cannot enter fastboot, try the following community-recommended methods: Paid professional software that can re-write the factory