What does the C15 capacitor do and why do you think it shorted?

I am having trouble getting my turbo gsr to start after fiddling with the ICM. I was being lazy and did not disconnect the neg battery terminal when doing so. I have spark, I have fuel, I tried flipping the distrib 180. Timing is on. Still no start. So I inspected the board and noticed C15 looked SLIGHTLY crusty but not totally fried like a capacitor would normally look. Nevertheless I soldered in a new C15 (33uF 35V) 0.18 capacitor out of another junk board I had. Hopefully this will fix the problem, I will test it in the morning.