Is my Logic board dead?

I have a late 2009 model IMac 27”, Checking the Diagnostic LEDs only LED 1 is on.

Testing the power switch works fine

Testing Logic Board power, the incoming voltage on pin 4 12v

Pin 12 starts at 4v then goes down to 0v after power button has been pressed

Pin 11 then shows 12v yet no led 2 or any fans/hdd activity.

Guessing I have a bad connection from moving around the motherboard but if anyone else has anything else to try?

Update 27/05/19:

After looking at it without being so tired

The graphics card was shorting on the heat sink

The system boots without and issue if the heatsink is removed from the graphics card

I am in the process of getting another heatsink will update if successful. (One that is intended for the graphics card installed)