As per the section 5.2.3 of the STM32H747I-DISCO board user manual, the default configuration of the hardware is to use SMPS mode but the default mode generated by STM32CubeMX when you select STM32H747I-DISCO board is LDO. Because of this mismatch, the board is bricked.
ST should have used the same power supply configuration in both the hardware board and default CubeMX configuration.
