The locked bootloader is having a lock at all. Without that, anyone can enter at any time.
In reality, home door locks are merely suggestions, they're trivially picked or broken open, windows can be entered through. But if you DID have a secure building, you wouldn't want any of the security systems to be replaced.
You get full access to operate in a secure building once you've used the key/biometrics/passwords/interrogation. You don't have access to replace the locks with tinkertoy homebrew shit, because we know that's not as competent.
I usually freeform people through City of Terrors for Tunnels & Trolls, I have a cheat sheet to where stats and major rooms are in the book if I care, but mostly just eyeball good MR for 20 Orcs or jaguars or whatever.
"Amber Waves" in the Apocthulhu Quickstart is really nice, a little road trip, cult, bad food, human sacrifices, fun for the whole family (if by "fun" you mean "dousing in gasoline and setting on fire"). Apocthulhu's quickly become my favorite horror game, because there's so few happy endings. One-shot, then do something different.