There are some things you can do to verify if you need to RMA. If possible, get you hands on a PCI-based USB Expansion Card. You can use the port there to get into Windows and see if Device Manager sees the USB ports on the motherboard. Second, you'll be able to gain access to the BIOS to verify if USB is enabled which would seem a crazy option on a USB-only mobo.
Install the 3304 biios.
That solves USB problems.
For me the fix is just to disable UEFI boot! I am with the SOX5810J.86A.4598.EB BIOS