Do the diagnosis properly, which is easy. If it turns out you need a starter motor, go out and get one. Don't make assumptions about what's wrong and blindly throw parts at it.

 

Batard, good vid and learning curve for anyone with non starting woes. I'm not sure whether it's you and your lad but whatever, he probably learned a lot then.

PS. ....................some great trick electrical diagnostic kit also, wish I had similar kit to play with.

 

I have an 04 and I experienced something similar last week after installing a winch and bumper. Turned key and nothing, lights in dash went out, click from starter. Wiggled the cable and it would start. Tighten everything up and it would fail to start again. My problem turned out to be a bad connection to the positive battery post. Double check and thoroughly clean that positive cable clamp. Mine looked ok but upon further inspection it had a slight film of hardened corrosion (almost opaque) all around the inside of the clamp. I had to really scrub it with sand paper, I didn't have a good file and my battery post/ cable brush was a bit too small to be effective.