My discovery of Vault 96 feels, despite my abhorrence of magical thinking, like predestination. A biological research facility, unoccupied, simply waiting for me to discover it. Everything in its place, its systems ready for my arrival.
Examination of the Vault's computer systems and other records found leads me to understand that previous residents introduced a virus into the mainframe in an attempt to end some kind of hostilities with it. This may explain the unsealed door and their untimely fates.
The mainframe requires some work to bring fully online, but any hostile programming it had has been eliminated by the virus they introduced. Too late to help them, perhaps, but sufficient to clear the path for me.