Won't start sometimes only what could it be

Not enough information. Is your weather really cold? Have you tuned it up in the last 30k miles?

Yes the weather conditions cold, just replaced battery & still doing that I just purchased car June 2017 complete inspection done. Don't have 30? Yet

What happens when you try to start it? How cold is it?

It doesn't start ..light in dash come on but nothing happens for 10-15 minutes trying then it turns on after

It's currently 38°

I will try one last time. Does the engine turn over or nothing at all? Have you cleaned and tightened the battery connections? If you don't answer questions I can't help.

38 is not really very cold but how cold is it when the car won't start?

No it doesn't turn over nothing at all , the battery connector have been tighten when replaced battery, the temperature has been 20-38°

I will be taking to dealer 2nd time they can't seem to find the problem since their no diagnose code

I would remove the battery connections and clean and tighten them again. 20 degrees is not cold enough to cause a significant problem.

Sounds like a loose or corroded connection on battery cables. Double check all connections