How to access DFU mode of Pixhawk6C module?

Hello everyone!
I have some difficulties. After I changed the board ID from 53 to 10051 with the command "APJ_BOARD_ID ", I couldn’t burn the other firmware.
I want to access Pixhawk6C’s DFU mode and use ST-LINK-V2 and the STM32Cube Programmer tool to flash bootloader.
But I have been unable to find a good reference, can someone give me some help?