Here's an article found on oem plus ages ago.
Phase One: Mirror Cover Removal
1.1 Push the inboard side of the mirror (closest to the car) forward so you can insert your fingers into the small opening between the outer edge of the mirror housing and the glass itself.
1.2 Gently pry toward yourself until the mirror glass pops off. It's a good idea to have your other hand close by so the mirror doesn't bang against the car and break or chip the paint. Note the orientation of the wiring connectors on the back of the glass. You'll need to reattach these later, but unplug them for now and set the mirror glass aside.
1.3 Looking into the empty mirror, locate the three Phillips screws that secure the mirror swivel plate to the assembly and remove them. Set the screws aside to be reinstalled later.
1.4 Once the swivel plate is loose, remove the connector that secures it to the car and set the swivel aside to be reinstalled later. Gently prying the tabs apart will allow the plug to be removed.
1.5 After the electronics are disconnected, it is time to loosen the mirror housing in preparation for removing it.
These next few steps are the most delicate part of the entire install. As shown below, gently pull the lower trim toward you and upward until it comes free of the securing slot on the bottom of the arm. I am holding the camera in this shot, but you should use both hands. It will not move far, so don't yank on it.
1.6 There are two tabs that secure the blinker to the mirror housing. The one on the left (circled below) can be easily release before you pull the housing off. Do so by gently lifting on the outer end of the housing while you pry the tab towards you with the regular screwdriver. You only need to lift the housing far enough to keep the tabs from falling back into place when you remove the screwdriver.
Don't overdo it.The second tab is more difficult to access (and impossible to photograph) but you can see it by looking down into the hole that the screwdriver is protruding from in the photo below. Assuming that the outer tab is released, lift up a bit more on the mirror housing as you pry the second tab away from the painted housing.
Again, don't overdo it. Don't let go at this point!
1.7 It is now time to remove the housing. Continue lifting at the outer end and pry at the hinge with your fingers or the regular screwdriver. Fingers are preferred. Draw the housing upward and toward the front of the car. It will come off pretty quickly. If you hear some snapping noises, the blinker tabs snapped back into place before you could get the housing off. Try to be more careful on the other side.
Note: Here you can see the second tab a bit more clearly. Or, where the second tab
should be, if I hadn't broken it off. It is accessible, as long as you are patient.
