One of the major issues is cellular towers that crash, and along with it emergency communications (run off the same towers).
Then we have issues with pumping gas as most do not have generators.
Many times, you have wires down for days.
Then you have traffic light issues and crashes due to this.
Mass transit (trains) stop.
Food in grocery stores spoil.
Ports stop functioning properly.
Water becomes contaminated.
Hospitals have no power after a certain time frame as well.