Not all would be fried. The point made, you would only have to cover the strategic locations in a fast recovery process. Ergo 10 days of darkness.
I guarantee the TVA is the hingepin, upon which the grid swings and have a list of the vulnerable areas that would be classified.
It's doable. But it would take a master brain to carry it out. One, I have no doubt, is already in play and working for Potus