Won't power on - but the "power on" sound is present.

Won't power on - but the "power on" sound is present.

My console is plugged in with a working power supply, when I hit the power button, it “chimes” but doesn’t not power on - no lights on the rings. Disc drive does a similar thing - plays the “disc tray open/close” sound - but nothing happens. What could be the issue?