It's possible the power supply died. Check voltages.
My favorite troubleshooting saying is "think ASAP," Always Start At Power.
You have 120v AC coming into your cabinet. From there, it will split and go to your monitor and the power supply. At the power supply, you'll have 120v AC and probably 12v DC and +5v DC and -5v DC (hopefully it is marked somewhere).
Do you have any game audio coming from your speaker (aka, game playing "blind")? If that is the case, your power supply is probably fine and you should move your troubleshooting to the monitor.
Hope this helps!