2000 Jeep Grand Cherokee Laredo - want crank will turnover

I think your getting terms mixed up.

Cranking is typically what people mean when the engine turns with the starter motor.

Turning over is typically what they mean when the engine actually fires up.

Because you (or your brother) replaced a freeze plug, I suspect there is a disconnected or damaged sensor. The computer has to know precisely when to squirt gasoline and when to light the sparks - it does so via crankshaft and camshaft sensors.

For an engine to run, you need fuel, air and spark. And at the right time. Air is normally the easy one. Fuel you can sometimes smell. Spark you can sometimes measure (hard to do on the 4.7).