rick 9/23/2012Lots to check but most easy . Good battery , good CLEAN cables , neurtal safety switch , last bench test the starter after you check to see if it's getting power .
HouseCallAuto 9/23/2012If you mean by saying it "doesn't turn over at all" you are saying that the starter is not turning / rotating the engine, then your cause could be that coolant has flooded one or more cylinders and there is hydrostatic lock. i mention this because the 3.8 liter buick V6 is known for this happening and the cause is a bad upper intake manifold plenum. Update the post with clarification.