Albe100
·The red dot was a seal that was put on the caseback/case. if the seal was broken or not visible, it indicated that the watch had been opened.
but as a previous post mentioned, they stopped using this a few year ago. I know that my 300 Master CoA from 2015 had the red dot on it, so not sure which year they stopped.
as for the serial, he may not be able to zoom properly on the SN, amateur with his camera phone. but meet up, and check as advised above that the card and the SN match.
Good luck!