Won't Turn On With I/O Board Attached

Got this macbook air which will not turn on at all when the Left I/O Board is connected. It will turn on fine as soon as the connection to the Left I/O Board is disconnected from the logic board.

So far I have tried:

New I/O Board Cable

New Left I/O Board

New Logic Board

Leaving all peripherals disconnected from Left I/O Board.

As soon as I pull the cable out of the logic board the macbook turns on automatically and begins to start up.

Should also be mentioned that it originally powered up but gave only a dim display which appeared to be related with the magnetic sensor on the I/O Board - diagnosed by running the board without the I/O Board attached. Now it refuses to power on with either I/O Board attached.