Screen black, DVI output good, see desktop with flashlight

I'm looking for suggestions regarding these symptoms.

1. Screen flashes for less than a second at boot up.

2. Boot sequence finishes and all is well. Keyboard lights up, caps lock light works, function keys work.

3. Flashlight shown through logo shows desktop and working cursor.

4. Hooked up DVI to external monitor and it works fine. I can screen share and use the Macbook as well.

What needs replacing? LCD inverter? LCD cable? LCD?

I'll buy whatever it needs, but don't want to go down the rabbit hole. Thanks.