d4520cd3ac
Seems that this is a typo. When I used the hex file it worked so presuming that means it's right ;)
eeprom_reset.hex is to reset the eeprom on the Atmega32u4, like this:
dfu-programmer atmega32u4 erase
dfu-programmer atmega32u4 flash --eeprom eeprom_reset.hex
You'll need to reflash afterwards, because DFU requires the flash to be erased before messing with the eeprom.