It's explained in the of the map above. I didn't see it either until just now. From trial and error and now reading the post and images, basically there are 4 things to look out for:
1: Cassidy moving around the the Vault Hatch. If she gets in thru the vents its a game over. She seems to only move counter clock wise but I'm not sure.
2: Sammy trying "to commit arson". Her voice line is the tell that she is up to something. Just honk at her.
3: Colors changing. Once you see the Ratings bar drop go back to the security room and change to the correct color. The image seem to suggest that you could find out what color it will change to by looking at Misty's DJ console but that camera is fucked so just go by the bar for now.
4: Nile and Maddy will show up to the security room door and you give Nile headpats and you just except the delivery from Maddy I think, I've only had the Maddy event once.
I could be wrong about some of this but its been getting me thru the night so far.