Error: the selected serial port does not exist or your board is not connected

Sometimes the programming jig is not firmly pressed on the Blink and causes that error. I’ve found that the reason for programming failure is usually:

  1. Re-press (not too hard) jig on Blink so spring loaded pins make solid contact
  2. Blink battery too low (check voltage between screw and reset pin - should be at least 2.7v)
  3. Make sure USB connection working properly to PC/Mac so ISP is seen.