The note seems to be more like a slapdash schematic than a fully-formed thought, with circles and arrows branching out all over the place, connecting the drawing of some sort of device with the phrases hairline trigger and potential override. There are ink smudges all over the place, like the hand of the writer darted over lines before waiting for anything to dry.
There's also a very large puncture wound ripping the note near clean in half.
NOTE FROM SLEEPER CAR 04