Hi!

If someone wanted to sabotage an LCD monitor, rendering it
unrepairable, but make it seem like a plausible random fault, what
would be the best way of doing this?

And you'd want to do this because...?

I can tell you that a set of wayward car keys can scratch the topmost layer
of the screen. You also really shouldn't spray glass cleaner right on the
screen itself...

Seriously, though...if you're thinking of deliberately damaging the monitor
in order to get a replacement or warranty work that you can't get
now...don't do that.

William