It appears that the preprocessor symbol HEXFILE_Arduino_COMBINED_dfu_usbserial_atmega16u2_Mega_Rev3_hex_Full was at some point removed in favor of HEXFILE_Arduino_COMBINED_dfu_usbserial_atmega16u2_Mega2560_Rev3_hex_Full. Not all references to this older preproc symbol were updated, resulting in an inability to flash the original bootloader onto a Mega 2560 Rev3.
NicoHood
commented
3 years ago
It appears that the preprocessor symbol
HEXFILE_Arduino_COMBINED_dfu_usbserial_atmega16u2_Mega_Rev3_hex_Fullwas at some point removed in favor ofHEXFILE_Arduino_COMBINED_dfu_usbserial_atmega16u2_Mega2560_Rev3_hex_Full. Not all references to this older preproc symbol were updated, resulting in an inability to flash the original bootloader onto a Mega 2560 Rev3.