RK 3399 no flash over USB

horstschlemmer

I have successfully tested the compilation of the sources and execution of the program under Linux and Android.I had a great time, the staff was really friendly and I had no problems adapting at all!
The problem that i have with a download of a new application part through the Boot Loader
After connecting the module, the following steps are necessary to configure
The first one, device is cut off all the power sources, such as power adapter and Type-C connection:
        1.Keep Type-A cable connected with host PC.

• ress and hold RECOVERY key.
  
• Connect Type-C cable to the device.
  
• After around two seconds, release RECOVERY key.
  The other way
  
  

• Use Type-C cable to connect host and device together.
  
• Press and hold RECOVERY key.
  
• Shortly press RESET key.
  
• After around two seconds, release RECOVERY key.
  
  

The Device Management, never find a the device name "Rockusb Device“

Several times I tried to this Steps but the loader mode is not available and the boot fails.

I try also this If device still can not be found after pressing "RESET", then try this: long press "PWRKEY" after short pressing of "RESET", before finally releasing "RECOVERY".

and nothing the bootloader  has no connection over USB

What can I do