May I ask which example program you are trying to load? What are the steps that lead to the failed connection? It looks like the board may be in reset or in sleep on the failed attempt.
Here’s how to re-flash a chip built from one of the examples that is continuously resetting or in sleep (from the project Readme file):
Sometimes the firmware in RSL10 cannot be successfully re-flashed, due to the
application going into Sleep Mode or resetting continuously (either by design
or due to a programming error). To circumvent this scenario, a software
recovery mode using DIO12 can be implemented with the following steps:
- Connect DIO12 to ground.
- Press the RESET button (this restarts the application, which will
pause at the start of its initialization routine).
- Re-flash RSL10. After successful re-flashing, disconnect DIO12 from
ground, and press the RESET button so that the application will work