Issue: Battery acts like it is dead, but brand new?

[GoDadGo]

Check your ground and positive leads because a poor connection can yield the actual voltage, but won't carry the load when you attempt to start the car.
Also, consider tapping the solenoid, because they can Booger Up from time to time and often will free up and make a good connection if bumped a bit.
If these simple steps don't work, have the battery load tested because you may have a new, but bad battery.

NOTE:.. Booger Up Is A Southern Technical Term For Malfunction!