Display won't work- replaced motherboard, display and cable >:(

The display on my 21.5" iMac is deader than campaign finance reform.

Regular question right?

Here is what I've done so far:

Replaced the display cable (the ribbon looking one)

Replaced the display

Replaced the logic board

No joy.

Before replacing the logic board I was getting three of four leds lit up...top one dark.

After, still three of four, top on dark.

There are two other cables on there but I don't know what they're called...

Any help appreciated. As you can see I have tried.

It will boot up....I have a separate monitor hooked up via a thunderbolt port.