Problem with Fastboot reboot and Can't install new firmware Mi 10T PRo

[fantidus90]

Hello guys, i have a mi 10t pro, today try after unlock devices 7 days to flashed and downgrade because my battery drain is significative, i had 12.5.1 eea firmware and try to downgrade to 12.0.19, but now phone is in continus reboot in to fastboot, i try to flash with last miflash tool, but after 2sec is tell me that firmware upgrade is complete and now i can't start my smartphone. i can try to flash last rom fastboot 12.5.1 but without result. How i can resolve this problem? thanks in advance