No crank no start after replacing the battery and throttle body?

Just replaced battery just replaced throttle body unit but it won't start, I can turn the key and there is power, but it still won't start. Originally the battery was bad so we got a new one, then with a muffler that we didn't repair yet it just starting to lose power and just shut off out of nowhere, so we replaced the throttle body unit and repaired the muffler hooked the battery backup. I thought everything was fine, but it won't start. It has power but won't turn over to start. Please help.