Reverse-engineering VGA
How did you find the ground pin? You should measure resistance against the chassis (when you measure resistance, do it without power to the board). The pin which receives ~0 resistance is the ground pin. The reason I'm asking is that that the resistance you get is weird. I'd expect 3 pins (R,G,B) to have 75 Ohm termination resistance against the ground.

BTW, those pins (3,4,6) that you have not detected any signals in, suggest that there is no video output (if you measured correctly). It may be required to first enable video output somehow, before you go on any further.