Yamaha DGX640 keyboard does not produce any sound

by Laurie
(Friendswood, TX)

After sitting idle for a couple of months, I turned on the piano and am not getting any sound from the keyboard or the demo, metronome, etc. When turning it off I still get that little blip from speakers. I have checked all of the obvious things, cords, "Local" setting, changed outlets, etc. Still no sound. Display lights up and goes thru its motions. The piano was bought new and we hv had it about 5 1/2 years. Up to this point no problems with it at all. Does anyone have any ideas for me to check further.