This post is all spoilers and walkthroughs for Marathon Eternal for Aleph One. For the Level list, see http://traxus.bungie.org/index.php/Eternal_Volunteers
Actually, the switch to expose the circuits to be destroyed is hidden behind a purple charger in the SE corner of the map, not on the upper deck, or at least, not just on the upper deck.
OK, so to this point, I have been fighting this galaxy wide Slaver race and their minions. Very fierce. I’ve gone back in time to find more powerful weapons, and they have followed, in force. I found the remains of a race that had such weapons, but another enemy had destroyed them. That enemy is now attacking me also, also in force. After I activate the weapon, I have to flee flooding plasma, staying barely ahead, up a winding and seemingly endless narrow staircase, without falling to the plasma below on either side, as I am sustaining attacks on all sides by flying enemies.
Ok, I’m dealing with that. Where it got annoying was that then explosions start going off, and each explosion blinds me for several seconds.
So, I have to do it blind-folded!? Nice. I suppose in the next level I'll get one hand tied behind my back too!
The blades won't destroy circuitry. So, use the grenades, to destroy it at a distance, for a small head-start. But get your blades back up fast, to clear enemies from blocking your path on the stairs. Then use the map to navigate the stairs.
