Server went down, admin with system access hasn’t been seen in months.

I kind of like the alliteration actually, but I also think most people in the US (this is a sad statement in education) wouldn’t understand it. Potentially lethal is probably better.

Please remember this when you (generic “you” here) read the words “non-lethal”.

“Non-lethal” is marketing to make it not sound as horrible as it is.