Started with 80 grit too because that is what the old guys taught. Took me years to figure out the scratches were the problem, not the fix. 180 is plenty for primer to bite and you are not fighting sand marks later. Ray did you a solid calling it out.

Wow, what exactly did your buddy's bad pitot check cost him after the fact?

Ngl 3 hours is rough but that's on them for not reading the error message, it's not some hidden trap. Calling it a top footgun feels like a stretch when most people hit this once and never again.