What were the chances of this happening anyway?

I just encountered a really weird bug while soloing Landing Bay.

The computer hack at the end of the level, where you have to line up the ones to "align the processes" and download the data, started up with the processes already aligned and went straight to downloading the data.  I never even saw the normal display you get, it just said "Critical Data" as soon as I turned it on.

Because the "process alignment" phase never happened, none of the aliens that were supposed to spawn during that phase actually spawned.  Normally they spawn endlessly until the tech completes the hack and starts downloading.

Because nothing spawned, there was nothing to knock down the door out of the room.  Being that I only had sentry guns and a hand welder with me, I couldn't knock it down myself.  The door is not welded and will not open on its own. I tried to unweld it and ended up reinforcing the door.  Unwelding it after this didn't magically make the door open.  I think it's set in the level design so that it has no trigger to open it.

The result: I was stuck.  I couldn't get through the door.  Melee attacks don't work on it.  My only recourse was to go find a couple of the spawns I had purposefully avoided to conserve sentry ammo and commit suicide.

Edit: I guess to calculate the chances of this happening, one might need to know a bit about the system...  What I'm asking for specifically is the chance of all four ones being lined up when the window comes up.  There are eight rows in each column, seven of which contain a zero.