Dell Inspiron N7110 :: No Display And No Beeps

Specs:
- i5
- 4GB
- cannot boot into Windows 7

I am working on a friend's laptop.  Originally, the laptop had a bad power adapter.  They heard a "popping" sound from what sounded like it came from the laptop itself.  Laptop went dead.  They bought a new power adapter but it won't even light up the LED's on the laptop itself.  The new adapter definitely works.  

Of course it's used for taxes, home business info, etc.  So they ask me to look at it since I have 10+ years in IT and can do most PC repair stuff without batting an eye.  Well, here I am.  Laptop is not under warranty AND it's still being paid on as it was financed by Dell.

Here is what I did to troubleshoot:

1) Verified power adapter got power and works with another Dell laptop.
2) Verified laptop will not power on.
3) Removed bottom screws, plate, battery, etc.
4) Removed keyboard, screws, and top plate.
5) Found a lots of black markings on the motherboard, specifically at the circuitry near the battery port.

Determined it needed a motherboard and maybe other stuff but wasn't sure.  Bought a new motherboard with a 90 day warranty from CHINA on eBay.  Also bought a new keyboard since a key was missing and new fan since it was in rough shape.

The repair steps:

1) Removed old motherboard and took off heatsink and CPU.
2) Reseat CPU on new motherboard, added Arctic 5, Reinstalled heatsink.
3) Added new fan and buttoned everything up.  Triple checked connections
4) THERE IS LIFE!  Power supply now feeds power to the laptop as LED's are lit.
5) Power button is pressed, nothing on the video but the fan spins up and sounds healthy.  No caps lock LED.  Hooked up to a monitor DOES NOT WORK.  No beeping, nothing.  I figure maybe the CPU isn't working so I try reseating it.
6) Tear it all down again.  Reseat CPU, new thermal paste, reinstall heatsink, button it back up.  SAME THING.  This time it's not fully reassembled.  

I tried doing the D + Power Button to test the LCD.  Looks like the screen does something, but it's dim and doesn't last long.  I can't see if it tries to do anything in detail, but I notice a little bit of light omitted from the side.  Tried discharging any static.  

Normally, I would throw in another CPU or something, but I don't have spare parts for this laptop.  How can I continue to troubleshoot this?  Maybe a bad motherboard?