Wendy,
Please ensure that all USB connections are secure and that your driver is up to date. We are currently at version 5.7.25. If you are connected via a wall box or connectivity panel, try and bypass it and connect directly to the electronics of the board. If you are still having issues, try another USB cable. If your board has speakers imbedded in the frame ensure that the standby light is green.
If none of these suggestion resolve your issue, please contact Technical Support at www.prometheankb.com, select Interactive Displays, Contact Us, please include the serial number of the board and in the Existing Case field, input case number 219322. If you could also provide the driver version as well in case an update is necessary.
Thanks!