Found another little slipup of either Jim himself or an oversight of his editor. Happens just before chapter 28 and shortly into it.
Spoiler:
The power is out because of Cowl, but after Harry is done talking to Billy he
As I rode down in the elevator, I had to admit that Billy might have a point. Except a little bit later at Shiela's apartment:
...before I realized that, duh, the power was out and I wasn't going to be able to ring her apartment.
Very interesting, unless elevators run on coals in Chicago, and are uneffected by a black out.