After playing Saavedro's heart-warming message, head all the way down the tunnel.
You've reached the giant electromagnet, but it doesn't seem to be powered. Surely you wouldn't have to do that...
If you look closely at the windows under the D'ni numbers, you will see circuitry. You'll have to make sure that the circuits in all five windows are lined up before it can be powered up. Use the six buttons on either side of each window to move the circuits. You'll know when you have it right.