SOLVED! I want to share how I fix it. My MacBook Pro had same problem. Last night I turned off my comp, but next day cannot turn on. I searched internet-nothing work. Sound like on/off button doesn't do connection to comp. I removed bottom cover (unscrewed first) and located spot under button on/of. There tree connectors together and one little bit on side (they are very small). I disconnected and connected back one by one - that all what I did. And my comp work again. Do not touch by fingers and do not use any metal to those connectors, because can be electric shortage. I used tooth pick to lift connectors and plastic side of small knife to press back those connectors. Do not disconnect all at ones- you can forget where they belong to- do it one by one.
Same time you can clean there dust around - just blow air. Before long time ago I did fix another comp for other problem-some connection wires was fallen off right under key board, some was just sit on top of their nest and wasn't pressed down.......