failed to enter boot loader mode

My school purchased the Swept Away bundle and when updating the firmware there is one cortex that will not update. It will work when plugged into the controller with a USB cord. The firmware recognized that it needs to be updated, but when it tells me to download the software, robotC and the Vex Firmware Utility will not update. I have tried to manually update through robotC and it keeps telling me that it failed to enter boot loader mode. The keys will not work until this cortex is updated. The other robots updated correctly and are working. Any help would be appreciated.


Thanks for taking the time to post your problem.
You should be able to restore the suspect Cortex using the VEXnet Upgrade Utility 4.1.6. Can you please attach a screenshot of the VEXnet Upgrade Utility while the Microcontroller is connected to the PC with the USB A-to-A cable?

I await your response.


Thanks for the response. I have attached three screen shots. The Vexnet firmware recognizes that it needs an update, but just times out and does not allow for a download. The RobotC tries to start the bootload but also times out. When I try this the vexNet light goes from green to off and the robot light starts to blink red (about every second). Not sure if this helps.
Thanks for your help.





Thanks for you r detailed response.
Which version of ROBOTC are you running? Can you attach a screenshot of the “Software Update” window? All you have to do is click on: Help> Check for Updates.

Check for Updates.jpg

I updated RobotC to the latest version and tried again. I get the same result. For some reason this cortex will not enter into the bootload mode. It just times out.

I have attached the image for you


When I updated to the latest version of RobotC, I started playing around with the config button to see if I could erase the software and re-install. I took the cortex off, removed all connections, held down the config button and plugged it into the USB A-A to the computer. All the lights turned green and allowed me to erase the firmware and re-install to the latest version. It seems to working properly now.

I compared it to another cortex that we have and each time when there was a problem, the vexNet light would go out. Now the light stays on.

I appreciate you taking the time to help me. It’s nice to have people to turn to when your learning yourself while trying to engage students.
Thanks again,

Glad to hear everything is working.
Thanks for your business and support.