This is in the EP500 troubleshooting guide.

Green Light On But No Audio

1) If using high level in, check that speaker leads are not reversed
2) Check input cable is completely inserted and working
3) Turn amp off and then on again
4) Speaker wire internally may be disconnected
5) Check the top 250mA fuse and the bottom 15A fuse (View Fuses)
6) Check your receiver menu settings to see if sub is turned on
7) Check that the fuse box is in 110 position for 110 use (220 position will have green light with no audio on 110 circuits)

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne