Why won't my car start with a new battery

Two things come to mind. First, the new battery may be below the voltage threshold of the computer for starting. Many newer vehicles will not allow the starter to engage if the battery voltage is below a certain point. Even if the battery is brand new but has been on the shelf for a few months. Second, many newer vehicles must have the computers powered up at all times. Even during a battery replacement. A memory saver device must be hooked up to the vehicle before the old battery is disconnected. If not, the vehicle will have to be reprogrammed (flashed) by your local Chevrolet Dealer. Hope that helps! Jim

Take a close look at your battery connections and load test the battery itself. Clean your terminals and the cable connections so they are completely clean of any corrosion. Then try starting it again. Still no go, follow Js0816's advice.