Around the last year when I was in high school and I was in music class, someone brought in his guitar and a single FX pedal.

Now I was not into guitar then so I didn't really care much about his setup although he had a nice FX pedal

This pedal was grey and had a blue back-lit screen.
I believe it ran on a 9V battery as well.

Anyways i'm looking to see if I cant get any more info on that pedal.
That's really not enough info to do anything with, sorry. Most pedals run on a 9v battery, and a blue screen isn't that much of a unique feature.
most multi-effect processors have backlit screens. the boss gt series ones i think are green or yellow backlit. the line 6 floorpod stuff is backlit, and they might be blue. not entirely sure. just go to musiciansfriend.com and search for multi-effects. chances are you'll find what you're looking for