New engine will not start

Hi I had a 'new' motor put in and not the van won't crank. I drove it to the mechanic and over a month later I had to tow it away. Apparently it can crank by fiddling with something under the hood but it won't crank with the key. I only had a three month warranty on the motor which will be up soon. I don't even know if the motor is good because I can't drive the van. We have found a lot of things that are not even connected. I took it to them with a full tank of gas but now it's on E. I believe all the spark plugs are fine. It doesn't do anything when I turn the key. I've purchased a new battery and neutral safety switch. The original mechanic claims to have run every test possible. I've also heard it could have been the microchip key so I ordered a new one and programmed it. Nothing has worked.