DRV8818: After running on power for a few seconds, the motor stopped moving and the MCU may be damaged

Tool/software:

After powering on the PCBA, the vref is adjusted to 1.6V and the output current is limited to 2A. After burning the firmware, the FW controls the motor to move continuously, but in reality, the stepper motor stops moving after a few seconds. Moreover, the MCU and driver chip on the PCBA are very hot, and the MCU cannot be burned again. It feels like the MCU is damaged. What may be the possible cause? The MCU power supply is normal.I tried two PCBAs in a row and it's the same problem。