Power/Pack-a-punch - You will first need to turn on power and pack-a-punch.
D.I.E Shockwave - You will now need to get a D.I.E Shockwave out of box or get the free D.I.E Shockwave.
Ice Upgrade - You will now need the ice ammo for the D.I.E Shockwave.
Aetherscope - Get all the parts and craft the Aetherscope.
Ghosts - Now do the first step of the D.I.E Shockwave Upgrades and get all three ghosts.
Electric Upgrade - You now need the electric ammo upgrade in D.I.E Shockwave Upgrades.
Fire Upgrade - You now need the fire ammo upgrade in D.I.E Shockwave Upgrades.
Gas Upgrade - You now need the gas ammo upgrade in D.IE Shockwave Upgrades.
Wrench - Make sure you have access to all ammo types. go into the Medical Bay and they should be a big purple canister hanging with four legs. If you have electric ammo equipped you need to shoot the leg to on the right when you are facing the main entrance. If you have ice ammo equipped you will need to shoot the left leg when you are facing the main entrance. If you have gas ammo equipped you will need to shoot the leg on the right when looking at where the box spawns. If you have fire ammo equipped you will need to shoot the left leg when facing the box spawn. You will need to do all of these and once all the legs are raised, go into the Dark Aether which is at the exit of the Medical Bay. Go back in the Medical Bay and go to the upper part which you will find another ghost to interact with. After that's complete and you are out of the Dark Aether a wrench will spawn next to where the ghost just was.
Tank - Go to the tank that is in the spawn room/Yard. Interact with the tank three times. Now a zombie should come out of the hatch which you need to shoot and kill. Now throw an explosive at the hatch so that it gets damaged which will cause it to fire. Go over to the crash site and there should be an orb the you can pick up next to the Aether teleporter. Take it all the way down to the Medical Bay and put it in the red box at the upper part of it.
Megaton Merge - Wait until a megaton spawns and the damage it until it splits. Now take both of them into the Medical Bay, under where you had to shoot the legs and they should get sucked up into it. Once they are both in there interact with the computer at the upper part again.
Final Boss - Make sure that you have the perks, armor, and pack-a-punch that you will need for this. Make your way into Nacht Der Untoten and go into Dark Aether. Interact with the ghost that is in the corner next to where the free D.I.E Shockwave was. Once that's done there should be a photo for you pick up right where the ghost was. Now you should be teleported back to the pack-a-punch room and you have to listen to a megaton. You will need to protect the friendly megaton and not let his health deplete. Once you has destoryed three things and exfil will start. There will be lots of blue beams but do not touch them because they will quickly down you so stay away from them as much as you can. Get to the Pond and get on the helicopter and then that is the end of the Easter Egg.