OK, like Arboc said, just chill. Plants have been growing for millions of years. You can do this.
I say just take the lid off your germination box. When my first seedlings popped up, I also had a tray full of inseperable cells full of other seeds on a heat mat. I just took the lid off the germination chamber and set the whole tray under my lights, and had to watch more carefully to make sure the soil stayed moist. As long as you keep that heat mat under the cell tray, the soil will still stay warmer than the surrounding air. And remember, the heat isn't 100% necessary for germination, but it does speed up the process.
Not to further confuse you, but rather than risk killing a seedling, I'd just unlid that box of yours, and get some light on those little babies! What kind of lights did you end up getting? If they're CFLs on clamp-style shop lights, you could just clamp one to the side of the box to get it closer to the seedlings. If they're too large, and are long like flourescent tubes, you could just take that seedling tray out, put the heat mat under it, and slide the whole business under the lights.
You can do this man!
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