Dan.. The software to update the firmware for the cortex gyro needs to run on a PC not a Mac ... The software version for a PC is 1.1 and the latest firmware for the gyro is V13.
The other end of the USB is connected in the bind plug position (pin1) and to you plug a battery source to the pin next to the bind plug. You have to re power while the USB is connected for the firmware to begin writing... It will guide you through it...