It's covered under the Casio warranty for sure. There's something wrong with that board too. My first WK-3500 was defective. When you turned it on all you got was a blank blue screen, no sound or anything. He should contact the store or place he bought it from ASAP, and if he needs to go further contact Casio.
GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.