The board manual specs that the power supply should be 9 VDC @ 500 mA (or more) with a center-positive, 2.1 mm plug.

You cannot supply the XS Boards with 5V through the power jack because that is insufficient to power the regulators. You can apply 5V directly through the pins of the XS Board. But be careful not to place 5V on a pin labeled "3.3" or "2.5" or you will damage the FPGA. You should read the installation manual carefully and check the version and type of board you are using before doing this.