I got the USB and Debug Add-On board and followed the "unbricking" procedure but I am not able to get a device to show up when running "sudo fastboot devices". The fan stays at full power the entire time and I am not able to communicate using adb or fastboot.
Additionally, no lights are coming up on the add-on board. Do you have any further suggestions? This unit did work when I first received it. The procedure in the link does work on a new voxl flight so I am sure the expansion board is working.