THe down side of having the power cut like that is they'll usually need to do an inspection and bring things up to code before they will connection again.

If you trust the wiring that's there you could hook up a portable generator to the panels and turn the breakers on one at a time to see what they do. That will also give you some power for lights and to get some things done. Definately not safe to do tho if tresspassers have been in there or if things have been torn out or the building has any damage.

Since no-one has said it yet lets see some pictures of this place.