Auto dimming homelink mirror install questions

[08blkmca-3hatch]

Hi guys!
I have an 08.5 MZ3 hatch. I was able to get my hands on an auto dimming/homelink/compass mirror off a wrecked MS3. I have a couple of questions for those who have done this retrofit. First one: is it necessary to swap out rain sensors? I feel the sensor has nothing to do with the function of the mirror. I haven't looked at the number of pin outs on my existing rain sensor vs the one with the dim mirror, but I'm guessing its the same.
Second: the dim mirror had the wires cut for the power, switched power, and ground. Does anyone know the exact location for the 3 wires? I know where they get spliced to on the car, I just need to know which is switch, constant, and ground. One of the wires is black with a white stripe. The other 2 are solid black. How will I know if I splice them incorrectly?
One more question: will the stock base work with the dim mirror? When I say base, I mean the metal plate that gets glued to the windshield. It seems to sit well inside the dim mirror...just not sure if there's a different one for the auto dim.
Let me know what you guys think. Thanks!

 

[08blkmca-3hatch]

Well...I seem to have gotten the wiring down, but mirror isn't turning on. I tested the pin outs that go to the mirror and there is power at the end, but when I attach it to the mirror, it won't turn on. I hold down the power button and nothing. Any ideas guys? Thanks.

 

[08blkmca-3hatch]

Is it because I never swapped out the rain sensor? I figured the sensor has no connections to the mirror, so I decided not to swap rain sensors.

 

[08blkmca-3hatch]

I figured it out. Anybody needing help with this, let me know.

 

[Abnmarine]

What was the solution?