Dont just spray WD40 behind the mirror as advised per other youtube videos, there are 2 rubber grommets that hold wires going the motor mechanism. If water gets in, from washing a car, car wash or heavy rainfall, the folding mechanism may not operate (open and close completely)

In my case, it was simpy removing the mirror, finding and Removing the rubber grommets and spraying WD40 down the motor surround, then replace rubber grommets.

hope this helps and you save some WD40 (instead of blindly spraying it)