I am a helping out a school who have a VEX Clawbot which they have successfully built and was working using the USB A to A cable connected to the Joystick controller.
They were able to move it forwards and backwards and open and close the jaws.

However, they have never been able to connect using the VEXnet 2.0 Keys.
They also wanted the students to download programs to control the robot, and was not sure how to do this and so has me to help.

I have taken the Clawbot home and have been trying to diagnose the problems.
I first Installed RobotC 4.0 on my laptop.
Looking at the forum, most of the problems seemed to be fixed by making sure the latest Firmware was installed, so I did that:

I used RoborC to manually download firmware:
RobotC Firmware (VEX_Cortex_1050.hex)
Master CPU Firmware (CORTEX_V4_25.BIN)
VEXnet Joystick Firmware (JOY_V4_25.BIN)

Then I noticed that both the Joystick and Clawbot batteries were not fully charged, so I recharged them all.

I re-tried the VEXnet 2.0 Keys connection, this continued to fail.
The Joystick and VEXnet LEDs flash RED on the controller and the ROBOT and VEXnet LEDs flash RED on the Cortex.

Finally I re-tried using the USB A to A cable and although all the LEDs were green, none of the controls move the Clawbots servos!

Clearly this is a backwards step. Please, can anyone help me diagnose the problem here.
At the very least get it back to working with the USB A to A cable, and then
get it to work over VEXnet?

Please follow the steps outlined in the 'Getting Started with the VEX Cortex - Wireless' guide linked below, and let us know which step, if any, the process fails on. If the process does fail at any point, please provide us with as much detailed information as possible (including screenshots of error messages, the status of each LED on the Cortex and VEXNet Joystick, etc) and we will be more than happy to assist you further.

Getting Started with the VEX Cortex - Wireless: http://help.robotc.net/WebHelpVEX/index ... VEXNet.htm