You should be able to bypass the USB chip and program via the ICSP header. You need a programmer. You can buy something like the USBtinyISP for around $20, or just use another Arduino as the programmer.
You should be able to bypass the USB chip and program via the ICSP header. You need a programmer. You can buy something like the USBtinyISP for around $20, or just use another Arduino as the programmer.