First, you’ll need to set the serial port to the bootloader. But that port is only visible when the board is in bootloader mode, so pull the reset line low twice quickly to invoke the bootloader reset feature discussed above. You can quickly press the reset button twice. While the Cactus Micro is in the bootloader change the ‘Tools > Serial Port’ menu to the bootloader COM port. Quick! You’ve only got eight seconds. On Windows, the bootloader’s COM port number is usually one number higher than the Cactus Micro’s regular port number.