I initially thought it must be the power supply having gone out, as I've heard that always having your PC in sleep mode instead of shutting it down can burn out your power supply. But if that's the case, I don't understand why the little rgb ambient lights on the motherboard still illuminate. Could it be the power button on the case? But that wouldn't explain why it wouldn't wake up from sleep mode originally. I'm at a loss. Any help is appreciated.