How Do I Fix my HP 15 Power Problem

Just happened that I left the system on, only to come back and saw it has entered sleep mood with screen all blank. Tried hard shoot down, removing the batter for sometime, pressing the power bottom for 15 mns, but all in vain...Each time I boot it on, it goes straight to sleep mode with my cap lock lead light blinking but screen all blank. Also noticed that if I leave it on like that, it starts over heating. Please does anyone has crew what could possibly be the problem. Thanks.