display issues and troubleshooting steps

13" Macbook mid-2007, Core 2 Duo, MB062LL/A.

- it turned on, though no chime and no sleep light

- optical drive wouldn't respond,

- and no display.

I've scoured the internet, tried all the key combos for resets, and RAM is good too.

I replaced logic board and new HD and new OS install because the optical drive mostly works now. Still no display though it shows on external monitor, and sleep light still doesn't work. Seems there is a backlight when I increase the brightness, and when I change resolutions I see a flash of weird colored lines for a second. I've scoured the internet, tried all the key combos for resets, and RAM is good too. What is my next step? I am hoping you can tell me before I order unnecessary parts. Thank you immensely!