To turn on the power, you'll need to find 3 parts :
A fuse
The panel
The switch
The fuse can be found above the spawn, you can access it by going left from spawn
The panel can be found opposite side of the main road to spawn
The switch can be found behind the bus in the northern toxic area
Once you got the 3 parts, you can craft the Power Switch in front of the garage, to the right of the nuke teleporter
Same as the Power Switch, you have to gather 3 parts and build it :
The flag
The motor
The top
The flag can be found directly at spawn
The motor can be found on top of the bus next to spawn
The top of the Pack-a-Punch can be found at the top of the bus, in the Nothern East teleporter
Once you've got the 3 parts, you need to go back to the Area 51, then the building is really obvious.
To teleport back to the Area 51, you have to link a teleporter.
Then you'll have to pay 750 points to teleport.
The teleporter is at the subway
The link is at the southern toxic area
As usual, you have to gather 3 parts for the Brazen Bull, the shield of this map.
The crafting table is at the small area before you get teleported to Area 51
On top of the bus next to spawn
To the right of the northern east teleporter
To the left of the south teleporter
You can build the shield in one of the small areas right after you teleport, before getting to the Area 51