Please unplug the IO Expansion Board before uploading any program to your Arduino controller, because the RS485 bus and Serial Port are multiplexing Pin0 and Pin1 (TX/RX).
By the way, uploading may fail because the bootloader is broken. In this case, you have to re-write the bootloader.
If you have any questions please don't hesitate to contact us.
Thank you,Have a nice day.
Nexus Automation Limited