Why won't my car start..?

I have a '99 Chevy Blazer with a 4.3 liter engine. I was driving down the street last Saturday night and the car stalled. I went to go start it, and it wouldn't turn over. At first I thought it'd be the alternator because this has happened before with the same results. But the battery was fine, I even replaced it to make sure. I replaced the ignition module, and the coils and it still won't start, it just cranks. I checked all of the fuses and everything is fine. The weird thing is my dad brought home one of those cheapy OBD II handheld scanner things, and it doesn't work. I tried it on my Mom's car and my Dad's car and for both of them, as soon as i plug it in and turn the key, the scanner screen lights up. In my car it's almost as if there's no power going to that certain plug, but everything else seems to work, the windows, locks, radio, ect. Any help would be greatly appreciated as I am at a standstill here and do not want to go to a mechanic and pay a ridiculous amount for it.