Minh,
Assuming you have the firmware that is normally shipped with the board, RedScarf reports as "RedScarf III" in the "devices and printers" if working properly. If it is in bootloader mode, it will report as "Generic/Text Only".
If it is doing neither, then there might be a conflict somewhere. Try to unplug other devices to see if that eliminates a conflict (i.e. you are overloading the power that can be provided on a usb hub (another side note: a fully loaded RedScarf pulls down a lot of current!)). If you go into device manager, is there anything that says "unknown device"? If there is, try and right click and uninstall that. Can you put the keyboard into eeprom programming mode (hold down esc while plugging the usb cable in) or firmware programming mode (hold down both esc and F1 while plugging the usb in)? Either the caps lock led, or both the caps and num lock led should flash respectively. If that's happening, the controller and the core software is still good, and you can reload and go from there.
It's unlikely you can fry a keyboard with normal use.