"Illegal Voltage" means the power supply you have plugged into the radio is the wrong voltage. I know it will show that if it's too high, and I believe it will show that if the voltage is too low. Either way, it's good that the scanner protects itself from the improper voltage. If you can, measure the voltage output from the wall wart. It should be about 6 volts for the BCD-396XT. Any other voltage is 'illegal".:wink: