Chromebook 3181 won't boot/post.

Hello everyone! 

Main problem, chromebook won't post or boot up.  It's on(?), but it's just a dark screen.  You can see the differences in gradient when you increase/decrease the brightness. 

Power LED light is off.

I've done the hard reset (refresh+ power) and ESC+refresh+pwr and nothing happens. 

I've opened the bottom, disconnected the battery, reconnected, yet no LED. 

Plugging in the AC adapter (with no battery connected), I get the power LED blinking amber, which I'm assuming is a battery error.  Bought a replacement battery, same thing, but I was able to get the white power LED on solid.  Eventually, the solid white LED goes off and we're back to square one. 

So am I correct to assume it's probably the motherboard?  Chromebook is out of warranty.

Any guidance would be greatly appreciated.  Thank you.