Ubuntu 20.04 Reflash

I accidentally upgraded the Xavier AGX SDK to Ubuntu 20.04 and need to downgrade to 18.04. On two separate host machines nothing shows up using lsusb or dmesg --follow when plugged into either of the usb-c ports on the Xavier now. Is there any other way it can be flashed?

If the Jetson is in recovery mode, and for the AGX Xavier the USB-C is connected, then you’ll see the unit with lsusb regardless of whether any of the software is valid or not. Recovery mode is its own miniature operating system and has no dependency on anything which has been flashed. Just make sure you hold down the recovery mode button, and then either power up or reset power, followed by letting go of the recovery mode button. If this fails, then something else is wrong, e.g., wrong USB connector.