To pack-a-punch a weapon you need to open the two bank vault doors in town. Then have someone place a turbine at the electric door symbol on the bottom of the drop into the powerstation (this door has a similar symbol to the door behind the bank vault doors you blew open). This opens that door behind the two bank vault doors and the pack-a-punch room. You then need to assemble the pack-a-punch with the parts found in that room and it will cost you 5000 points to pack-a-punch a weapon.
If the electric creatures you are talking about are similar to the one you release, then you should be able to use the Galva-knuckles or the EMP to kill them.
The Pack A Punch is located at the bank, when you destroy both vault doors. There will be a wall that has a green sign with an electric bolt on it. You will need to have someone put a turbine from the bus station next to the 74u at the Power Station. Once this is done, the pack a punch room will be open in the bank. From here, you will find all the parts to build the Pack A Punch.
B) How to kill the lighting creatures that appear after lv 20?
The Pack a Punch can be accessed by putting the turbine in the underground research facility. You put it right behind the point you drop down in. There will be a lightning bolt image on the door. Then when you go to the town; go to the bank, blow the 2 vault doors open (grenades or any kind of shot from an explosive weapon), and then the area within the 2nd vault door should open up and let you go below ground there. Then you will just have to put the machine together using the parts around that area.
I'm not completely sure, but I think the Pack a Punch room will close after you leave it for a little while.
And about the electric zombie. We managed to kill it, but it takes several shots. We usually just kept knifing it when it got close; it took forever, but we ended up killing it that way.
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