Reset fuses on atmega328p using Arduino
You cannot set the fuses using the Arduino bootloader, since they cannot be self-programmed. You must use either serial or parallel programming via ArduinoISP or an external programmer to set them. Since the chip is configured to use an external crystal you must either connect a crystal up to the chip appropriately (see sections 9.3 or 9.4 of the datasheet) or use parallel programming. You will then be able to use the lfuse, hfuse, and efuse memory types to read and write the fuse bytes.