No image on display, could be the v-sync cable?

Disassembled most of the computer to do a thorough cleaning as it was overheating because of dust accumulating over all this years, it was very carefully done and there were no parts broken.

Finally reassembled it and everything seemed ok, upon turning it on there's no image on the display

-backlight is on

-you can hear the chime

-fans rev up to normal speed

-hard-drive loading

-it has all 4 diagnostic less lit on green.

Tried the external 2nd display we normally use with it and it gets normal image, so everything must be loading, we can not access to desktop since the log-in screen is in the display not working as it is the primary display.

All ready tried SMC & PRAM reset.

resecuring all connections and trying again but still no image.

upon reading here and some forums I may have reduced the possibilities to the v-sync cable and tried connecting it more firmly and connecting it the other way around, but same results, there are no broken or bend pins, or other mishaps, so i'm thin ink of ordering a replacement cable, (not so cheap as it will be international shipping)

i have disassembled and reassembled many more successfully, and this is a first time event on me, so would this be my best bet as a solution, or am i looking at something else before ordering a replacement cable.