A "Link Error" will appear on the screen when the computer can not communicate with the I/O Board. This most likely is caused by a loose serial cable connection on either the communication board (Small 2 inch square board) or on the Computer itself. Start by unplugging and reseating both side and power cycle the game. If the issue is still not resolved test the voltage conning off the 2 pin connection in the lower left corner of the I/O board. You should see 5 volts there. If not we need to replace the Main software in the I/o Board or the LED control board has a short that is bringing down the communication channel. To test this unplug all connections the the LED control board and restart the game and see if the link error is gone.