ODD = Optical Disc Drive. From what I've read it will work with HDs, but they are not bootable is all.

So if you could get power to the 3rd HD, along with a SATA data cable on one of the ODD SATA connectors you may not need a card.

Will the cable from the 3rd sled running to the logic board stretch to the ODD SATA connector? I wonder if the SATA connector is bad on the board, or if it's not getting power to the drive, can you hear the new drive spin up or see a light on it?

Maybe get SATA data and/or power extension cables?

Just some thoughts.