DDJ - SX2 (Thru Mode - Source is on PC) - pitch fader and no sound

Hey All,

DDJ - SX2 is not working - it stuck on the thru mode, even when i switch to PC it still says thru on deck 2. I try to switch to Deck 4, and no sound is coming out.

furthermore, the pitch fader is unresponsive.

I have a Macbook pro and the latest software on serato.