Yellow blobs on nes board acidentially removed.

That sounds like flux to me. It’s used in conjunction with solder in order to make the soldering process easier. But once soldering is finished, it serves no purpose for the circuit, and should be removable without affecting anything. I suspect your display issues may be related to something else entirely. You could try re-melting the solder on those suspected pins to make sure they have proper connection to the board, Or it could be an issue with the new 72-pin connector.