Actually, I remember CHIMERA posting that he cleaned his PC in a dishwasher. From what he said, as long as you let it completely dry before turning it on again, you're all good. COMPLETELY DRY.
I suspect you missed the ATX12V cable when you reassembled today. Doing my first build, I overlooked it, and the PC would turn on but I got no video or anything. Look for a hanging 4-pin cable from your PSU and hope that you didn't cause life-long damage turning it on without it plugged in.