Loaded a bad video driver on my Jetson TX2 and now need to reload Ubuntu.

The board does not even register on the USB port to the laptop using lsusb. Is there a way to do a serial connection via the USB bus to log in and reset the drivers to factory defaults?

Normally the USB port is a host, not a device (you can plug devices into it, but not another host). In recovery mode it becomes a custom device, but only the flash driver will understand it. It would take special programming to do this.

Are you trying to use USB for file access?