can someone please explain to me why an electronic item would be affected if it wasn’t plugged in or turned on at the time of the attack? If my car was just sitting in the driveway why would it not work if it was started after the attack?
Unpowered electronics are more likely to survive, but a strong EMP can also take them out. The EMP generates a field that is coupled into the wires (or pcb traces) and appears as a transient voltage. This by itself can damage the electronics. It typically does a lot more damage with power applied because the powered device can amplify the effects.
As I mentioned earlier, if you have an old car it is more likely to survive; whether it is turned on or not.