Taking a CPR class two years ago and staying calm and remembering what to do during an actual emergency are two different things. How was the crew slow to respond? you are in a contained area, and if you shout your son isn't breathing, I don't think anyone will ignore you...
If someone is not breathing, start CPR. it's not that hard. Laypeople are taught to push on the chest hard and fast. If their heart hasn't stopped yet, it will shortly.
How did the Defib malfunction? need more information. regardless, push hard and fast.
The family is hurting, and I don't blame them for suing; to be honest, I hope AA settles for compensatory damages, and gives them some closure for their son dying on the their airplane.
True story: if you give me a zoll defib, and tell me to use it, I will look like a person f*$%# a football. if you give me a lifepak, I will look like a trained and competent provider. different brands have different quirks, and they do operate differently, while doing the same thing. So yes, there are subtle differences that can affect the comfort of a person using it.