When I had this issue it was a source/switching issue.
I changed sources and it fired right up.
Then I went back to the original source that wasn't originally working and it worked fine.
Is the sub set to "On" or "auto" because I'm fairly sure that mine was set to auto and there was an issue with it auto detecting the input signal.
I would try setting sub to on, then power on your source and try playing.
Secondly you could try swapping back and forth between a couple sources and see if it picks up. Mine did it once right after transport and has been fine ever since.