Well by removing the arms you gained access to the pivoting shaft. IF there was any water in the shaft and IF you were able to get the WD 40 down in there, that would fix your issue. IT obviously didn't which means that somehow you've got ice in your motor, I don't know how you'd ever do that, or the problem isn't ice at all but something to do with decreased clearances between rotating metal pieces in the cold.
2 choices, pull your fresh air grille and access all of the linkage and the motor or take it to a dealer and have them locate the problem.
This is a really odd problem for front wipers!! The rear can often seize due to lack of use and corrosion but rarely the fronts!
Good luck, sorry the easy cheap fix didn't work for you! It was worth a try though!!