"Le echó muchas ganas" . That is the right way to say that.

Exacto Jane, puedes decir "le echó muchas ganas, y por eso aprobó" Buen trabajo

"Echarle ganas" is the expresión and it has meaning on its own. Your intuition is right. No le eché ganas => I didn't try it Le eché ganas => I tried it. Le eché pocas ganas => I didn't try it hard enough Le eché muchas ganas => I tried it really hard. Le eché todas mis ganas => I tried it as hard as I could Where I live we use "ponerle ganas" and "echarle ganas" in the same way.