While it's in the bootloader mode, run \texttt{avrdude -p atmega32u4
-c avr109 -U flash:w:atreus.hex -P /path/to/usb} from the directory
containing the firmware\footnote{See
- https://atreus.technomancy.us/upload for how to determine the USB
+ https://atreus.technomancy.us/flash for how to determine the USB
argument and customizing the layout.}. The firmware should be
uploaded, and it will start functioning as a keyboard once switches
are connected. Next time you upload, you can use the reset key instead