qmk_firmware/keyboards/dz60/keymaps/billiams_layout4/build_flash.sh

# dfu-programmer atmega32u4 erase --force
# dfu-programmer atmega32u4 flash /path/to/firmware.hex
# dfu-programmer atmega32u4 reset

# run this in the qmk_firmware directory
make dz60:billiams_layout4:flash