What else can I check to see why my car want start?

What is your question?

I replaced the starter and battery. I put on new battery ends. The starter will engaged but want spin. I traced the ignition wire and checked it with a volt meter it read 12v when I turned the switch to actually crank the car. When I plug the ignition wire into the wire that runs to the starter the volt meter read 7.5v,so I took a jumper wire and bypassed the wire leading to the starter the meter read 12v but when I hooked it to the starter the still wouldn't crank. It just make a click sound like the battery is dead or the starter is bad.