Thanks for trying the game, and the feedback !!
About the usb thing, maybe the guard IA got stuck somewhere, blocking the whole game in "alert" mode (it happened on a stream), and since the player can't interact with the usb key if he's in alert mode (to keep him from getting caught since a dialogue box appears, keeping the player from moving until it's closed), that happened.
There really is only one way to do it without getting spotted by the guard, it's by going into the vents, and jumping down the security room hatch, and then quickly hiding either inside the locker, or under the table, then jumping out of the window.
I think i could add a way for the player to vault windows cause jumping through them caused a lot of people trouble. (since there is no mid-air control)