To unlock the Pack-A-Punch, follow the on-screen hints. They will lead you to opening 5+ doors on your way into the facility power room. Upon turning on power, activate both terminals to spawn an anomaly. Enter the Anomaly in the
Aether, and take the new tunnel marked near the
Crash Site. This will teleport you into a previously locked room, where you can collect the
Machine Part.
Take the machine part to the middle of the facility, and install it. The Pack-A-Punch is now functional. The first upgrade costs 5,000. The second is 15,000. The third is 30,000. You can also buy different ammo types for 2,000 each. Good luck!