It is said that because the bootloader does not match the Px4 firmware version, it is necessary to modify the parameters in the QGC so that it can be updated to the matching version of bootloader when installing the firmware

Step 1: modify  SDLOG_PROFILE   Parameters from “default” to “default” and “high rate.”   As shown in the figure:

Step 2:   Modification SYS_BL_Update parameter to 1  As shown in the figure:

Step 3: format the SD card and download the firmware again

Problem solving!!!!!