Downloading is the process of programming a target device with the logic functions contained in the design. Verification is the process of reading back the downloaded configuration data and comparing it to the original data to ensure data was downloaded correctly.
Before beginning downloading or verification, turn on the power to your board.
You must connect VCC and ground before you connect the control signals to XChecker. The input/output pins of their internal FPGA should always be at a potential that is lower or equal to their respective rail voltage in order to avoid internal damage.