that might be a solder bridge, or one of the resistors for the inputs isn’t soldered on correctly if all your sources were on the same input.
Check another input if you haven’t already, and maybe post pictures (closeups) of the board in the DIY forums.
Edit: Didn’t read that VGA input thing… try the following:
Check the resistors R4 to R9.
Also check all pins of the THS7353 at U17 for solder bridges.
After that check the TVP7002 for solder bridges on the inputs.