Power/Pack-a-punch - You will need to turn on the pack-a-punch and the power.
Hands - Go to the pack-a-punch and add brain rot to a weapon. Now go to Hotel Room 305 which is in one of the buildings. At the back of the room there is a boarded up door. Now get a brain rot zombie at that door and the zombie will open it. Enter the room and interact with the zombie on the bed.
Battery - Wait for a Panzer to spawn and once it does kill it and pick up the battery
Klaus - Go to the Safe House under the map and interact with Klaus who is on a chair.
Upgrade - Now go to the "Death Strip" part of the map which is next to the pack-a-punch. Now in the dig up the debris in the ground until a microwave dish. Go to the Garment Factory area which is in the room with all the spray pain and there should be a empty armor stand. Interact with it and now you have to get a certain amount of kills with Klaus and then the little screen will turn from red to green. Call Klaus over to there and he will enter it. Now you will have to defend him for around a minute.
Floppy Disk - Now you need to find 2 floppy disks in boxes on the wall and by using your black light which you can get by calling Klaus to the locker that has the number 0 on it in the Service Room. 2 of them with a a glowing Klaus head. This has 6 possible spawns and only 2 of them have it. The first spawn is across from the zipline at the 5th Floor Apartments. The second spawn is on the wall opposite of Stamin-Up in the Hotel Lounge. The third spawn is in the Ghost Station on the wall to the right next to an opening. The fourth Spawn is in the Maintenance Tunnel before the Safe Room. The fifth spawn is on the West Berlin Street just outside the café. The final spawn is at the Blasted Suite across from the previous spawn. Once you found of them call Klaus over to it. Klaus will break the box open and you can collect a disk. Take Klaus back to the empty armor stand and he will upgrade. Now do that again with the other disk to get the final upgrade.