FMU v6c failed to restart after burning firmware

I designed FMUv6 with reference to the official reference design of PX4, and now I have successfully swiped into the boot, and successfully burned the firmware, but the flight control board can not be recognized after the restart.

My process is like this: First, I use stlink utility to burn into the bootloader, and then my computer can recognize my flight control, qgc can also recognize it, but after I burn the firmware, the step to restart is stuck, and my computer can not recognize my flight control.

It seems that the normal process is that after the flight control restarts, qgc can recognize my flight control and jump to the interface.

Any help would be greatly appreciated!!