Car will not turn on anymore

Yesterday I tried to turn my car on and heard clicking noises when I tried to crank. I assumed the battery was bad so bought a brand new one along with a new ground screw for the terminal because it wasn’t screwing in. Clicking continued so I changed the alternator myself. I then connected the battery once I was done and the lights turned on, so I went to start the car and it clicked once and shut off. Made sure that battery was disconnected before changing alternator. Starter is relatively new changed it couple months ago. Also when I touch the ground on any battery with the terminal screw it doesn’t spark anymore. What do I do?? Is there something I did wrong??