I have a nrf52833 small board. nrf52833 QFN
and the several board have the same finding:
at first time, the board can be flash and be debugged to main entrance.
but , afterwards. I cannot flash and even debug the board.
-- west flash: using runner nrfutil
-- runners.nrfutil: reset after flashing requested
-- runners.nrfutil: Flashing file: E:\Nordic\bluetoothproj\build\merged.hex
Error: One or more batch tasks failed:
* 1050635330: Device error: Setting the debug port SELECT register failed while powering up sys and debug regions (Unknown Error in J-Link DLL (error code =-1)).
This might indicate that the debug port is unavailable. Please double-check device power supply and SWD lines, and that SWD isn't disabled (Generic)
FATAL ERROR: command exited with status 1: nrfutil --json device x-execute-batch --batch-path 'E:\Nordic\bluetoothproj\build\generated_nrfutil_batch.json' --serial-number 1050635330
* The terminal process terminated with exit code: 1.
* Terminal will be reused by tasks, press any key to close it.
once upon a time. I debugging in the code. but suddenly, it report debugging stoped.
so, my question is : why the firsttime, the debugger can debug the board but afterwards. it always failed.
and the recovery and reset command would fail too.
nrfjprog --reset -f NRF52
[error] [ Worker] - An unknown error.
[error] [ Client] - Encountered error -102: Command read_device_info executed for 158 milliseconds with result -102
[error] [ Client] - Encountered error -102: Command read_memory_descriptors executed for 45 milliseconds with result -102
Failed to read device memories.[error] [ Worker] - An unknown error.
ERROR: JLinkARM DLL reported an error. Try again. If error condition
ERROR: persists, run the same command again with argument --log, contact Nordic
ERROR: Semiconductor and provide the generated log.log file to them.
NOTE: For additional output, try running again with logging enabled (--log).
NOTE: Any generated log error messages will be displayed.
it looks the chip is recongized.
how can this occur? how to run out of this trouble.
the following is my design: 
thanks.
