6.0 won't start

I removed my dash the other day to look at the back of my radio because my sub isn't working. After I put the dash back on and reconnected the batteries, the truck didn't start. I made sure the connections were good and checked all of the fuses. I replaced the starter relay because I don't know...

Fellas, I need some help here. My 6.0 will not start unless it is plugged in at night. If plugged in, will start with no issues. If not plugged in (overnight low 65 degrees) it will cough black smoke and just turn. After 15-20 minutes of waiting for the glow plug light to go off and turning...