when you respawn go to the helicopter pad and you should see a yellow beam.

Run and jump on it and then go to the next beam and then you keep going and jump on top of that small building.

Then go on the other side and you should see another yellow beam.

Jump on it and then jump on the big yellow bridge and go right and then get on the window cleaning thing.

Then get on the building ledge and follow the ledge to a small window.

Duck to get in and then you're on the second story of the map in the building.