1. obtained a STRAIGHT-THROUGH serial cable with FEMALE DB-9 connectors on BOTH ENDS. 2. used that cable to connect a Linux machine to the console port on the switch. 3. set "minicom" to the correct serial device (e.g. /dev/ttyS0) 4. set the serial line parameters to 9600-8-N-1 (that and only that) 5. made sure hardware flow control is OFF. 6. made sure the switch is powered up. 7. pressed CTRL/Y in 'minicom' - the console prompt appeared.
All of these steps had to be completed - if any of them were left out, it wouldn't work.