
@Saul > If you have signal showing on the channel and master meters, then you should have output on the RCAs. The XLR output requires that you have the DC power cable; USB only won't provide enough power. You can verify that the DC power is working by disconnecting the USB cable and checking that the lights are still on.
Check the RCA outputs first, then if they are working, try another XLR cable in the L output and see if that works.