check all your connections first on both side of the battery cables.
be sure your terminals are all ruffed up and clean with sand paper or a wire brush.
check the battery cable just before each end to ensure it did not burn or break inside the insulation, just behind the terminal where it bends.
turn the key on, jump the starter leads with a screwdriver to see if it bumps the engine over. If it does, you know for sure the problem is in your push button wiring somewhere. If it does not bump the engine over, your battery is shot or your cables are shot/loose/dirty.