The Vault 75 misison won't start after entering vault 75 through the malden middle school basemant.

So therefore I can't get the "science" bobblehead that's in there and get the alien blaster from the UFO crash.

What gives?

Yeah, it's a known bug. If you're on PC, there's a way around it, but if not, you're kind of screwed.

Yes, I'm using the PC.

Then you have to use the console to give yourself the key cards. I forget what the IDs are, but saw them on Reddit. After you clear the place out,m and go up the elevator, it'll give you the quest. Then you'll have to kill a guy and go use the overseers terminal to complete the quest. It was really annoying.

The UFO doesn't crash unless you have completed the vault 75 quest?

I'm not sure if it crashes if you complete the quest or just clear the vault. You can clear it without actually finishing the quest just by killing all the gunners.

There are gunners in the areas that you need the security card to access.

Unless you use noclip to pass through the doors and kill the gunners, you can't kill every single one of them.

I've tried that and I still didn't get or complete the quest.

This is happening to me as well, I am unable to retrieve the Science Bobblehead.

The quest "Explore Vault 75" will not activate when I take the elevator from Malden Middle School basemant down to Vault 75.

The gunner commander in the training simulator will not drop "Vault 75 Lab Access Card" because they quest is not active.

I'm on Xbox, not sure of a workaround. Hope this gets fixed soon....