With the hardware in Bootloader mode, each time the device is reset (by pressing the RESET button), FlashcatUSB will startup in bootloader mode. With the software running, the main screen will now show that the device is in bootloader mode (“Device Firmware Upgrade”) and that it is ready to be reprogrammed with AVR firmware.
To change AVR firmware, click 'Load File', select the firmware HEX file, click 'Program', and once complete, click the 'Start Application' button. After you have successfully changed firmware, we recommend that you set switch #2 to ON, to prevent the device from booting back into DFU mode.