I had this one too, go into the BIOS (hit the del key and the password is Fireport) and see if the BIOS has detected the ATA Flash (512MB).
If its not there take out the screw and pull the cover off, remove the screw holding the flash in and pull it out and in again. Finally put it back togeather. I have seen flash that looks seated and was not.
If the BIOS did see the flash you are missing a S90 OS on the device. Go to the Wyse.com web site and get the S90 firmware and the Wyse Simple Imager which will allow you to push an image to a device with no OS.