Pavillion DV703164CL....Powers on, lights up, solid black screen. NO flashing lights.

I have a Pavillion DV 7 -3164CL. Laptop will power on, fan spins  but goes straight to a solid  black screen.  No dimm light in back of screen.  Hard drive light dosent blink and I dont even hear activity. There are NO blinking lights on the keyboard. Tried external monitor, no go. Tried booting with no hard drive, one memory stick, no memory sticks, nothing. No beeps.  Owner  states that when the computer was in the middle of shutting down, he would unplug it,  Thats with no battery ! Thinking a bad motherboard !? Any suggestions would be appreciated. Thanx