Use RKdevTool Download Boot Failed

Device:Rock pi 4b+
After the board is powered on, only the green light is on, and the system is not started. There is no response after inserting the SD card and pressing Maskrom to boot. If you fail to use RkDevTools to flash the computer, it prompts Download Boot Fail.
Log:

17:15:10 084 RKDevTool v2.6.9.0 start run
17:15:53 632 RKDevTool v2.6.9.0 start run
17:18:32 932 RKDevTool v2.6.9.0 start run
17:25:48 165 RKDevTool v2.6.9.0 start run
17:26:57 973 Layer<1-3>:Download Boot Start
17:27:04 105 <LAYER 1-3> ERROR:Boot_VendorRequest–>DeviceIoControl failed,Total(71682),Sended(69632),bRet(1),err(0)
17:27:04 106 <LAYER 1-3> ERROR:DownloadBoot–>Boot_VendorRequest471 failed,index(0)
17:27:04 110 Error:Layer<1-3>:Download Boot Fail

ROCK Pi 4B+ has on board eMMC, when flashing/writing images from USB to eMMC, don’t insert the SD card. You don’t need SD card actually.