Old post I know.
The 639 glass also just clips on, if you tip it right down you can see behind and get a long small screwdriver down the back and clip it off.
The mirror has 3 screws 2 you can see and one behind the black plastic cover this glued and clipped on! it then comes down 10mm and it's off.
If you want the back off then take the glass out first, then you can see 3 clips, these push out with a screwdriver.