Electrical problem

My Suburban wont start. I the battery is fine, because everything turns on door buzzer, etc. And it's only 6 months old. When I shift from park to Neutral nothing. Shifted back to Park, nothing. All the the fuses that I could find are fine. Checked the relays and they all click when you turn the key but no start up. Left it for a few hours then went back out and it started kind of rough. Shut it off and started it up about 5 more times. No problem. I then shut it off for like 5 minutes and then it wouldn't start back up. Please help