If for some reason when you're downloading the Master CPU Firmware to the Cortex, the download fails and you're unable to re-start the process in ROBOTC, you can try the following steps:

- Start with the Cortex turned OFF (but with a battery connected).
- Push and hold Config button in on the Cortex.
- Attach the USB cable between the PC and Cortex.
- Wait for the Robot, VEXnet and Game lights to blink green.
- Release Config button.
- Turn the Cortex ON.
- Then in ROBOTC, click "Robot", "Download Firmware", "Master CPU Firmware", "Standard File".