As the title pretty much encapsules, I used the ifixit guide to replace the fans, because the left one started making...

Ok, I managed to fix it myself. The USB port that wasn't working (the left of the two on the left side), apparently during the fan replacement and the thorough dust cleaning, the circuit board that makes up these two, got the last bit of dust to impede function from that. So after a thorough cleaning of it and a test run with the battery disconnected, I found that the port works again and I am not getting any error message anymore.