Looks/sounds like a powersupply issue. Replace the power supply, if it still fails to power on its the motherboard.
i was playing around and i decided to spam the power button, then the lights flickerd faster and faster, then in started! then it cut off and restarted its self, i smelt abit of smoke so i switched it off, i tried to fire it back up but now the lights flicker very fast!..... could it be the switch or the power pack , it aint the motherboard as it all started right ?