"I had the same problem after the firmware update. I disconnected the gimbal servoes and the MP connected succesfully. Hope this helps. Now I have reconnected them."
I'm in the same situation, set ublox 6 to NMEA in MegaPirateNG_2.8_R3 but not loaded configuration into the GPS by file 3DR-Ublox.txt. Doing this later at home. Did you solve the issue at the end by using the conf file and soldering properly…"