The "loading zone" is the place where there is multiple powered-down droids and five or six containers. In the industrial zone, before Testing. (Where the Escort Droid takes you if you tell it to take you to "loading zone"...) One of those containers - at least for me - did contain a powercell. However I'm still stuck because that's the ONLY place I've been able to find one, beside the Central Maintenance droid giving you two at the start of the quest. I completed the industrial zone repar-side-quest BEFORE (way, way before) I even got this quest and didn't receive any powercells ever. There's a "Sith Body" or "Dead Sith" (If forgot) near the Environmental Zone entrance. However nothing happens when I click on it. It is "selectable", and the character walks to it when clicked, but then nothing happens. None of the Environmental Zone droids dropped the cells when killed (then again, I didn't have this quest back then). Didn't kill Kaah either, so didn't get one. So I'm also short one and looking for a command to either cheat one in, or advance the quest manually to the point where I don't need the cells anymore. (KotOR Savegame Editor, KSE cannot do this, as there is nothing regarding M4-78 available in the KSE datasets.)
I'm in the exact same situation now. With all but one different point on that list: 4: nothing, I can click on the body and the character walks to it, but nothing happens then. No looting window, nothing. Also to note, I did "2." way before I even got this quest (for the cells) and never received any cells whatsoever.