To test whether the build and download was completed successfully to the VEX microcontroller, click on the 'View Diagnostics' link at the bottom of the Simulink model. The following screenshot shows you the location of this link in the Simulink model window.
This will bring up the Diagnostics Viewer dialog that shows the build verbose output. By going through this verbose output you will be able to verify if the build and download process was successful or not. If you notice any error messages in the output, contact the MathWorks support team at email@example.com for assistance.
You can also launch the Diagnostics Viewer by going to 'View' menu on the top of the Simulink model window and clicking on 'Diagnostic Viewer' option in the menu (shown below).