Make sure your car is turned off. You do not need to unplug your battery.
Installation Steps (Similar to RS3)
Note: some of these photos are from the RS3 installation because they are so similar.
Open your driver side door and remove the trim using the trim removal tool that was provided in your package. It will pop right off very easily.
Remove the bolt pictured here so that you can remove the panel below the steering wheel.
Remove the two bolts on the underside holding the panel below your steering wheel. Then pull the panel off. There are a couple tabs on either side of the steering wheel that will really hold on to it. The couple cars I've done I had to really yank it off, nothing broke, but be careful once it comes undone to disconnect the headlights switch otherwise you run the risk of breaking that wire. Once you have this panel removed set it aside.
Remove the two fan vents under the MMI screen by gently pulling/working them out. You'll then see there is a nice gap to feed the bTres wire in the air duct down to the opening behind the panel you just removed.
This is where a second set of hands comes in handy. You'll want someone to hold the screen mount in place while you slowly put the fan vents back into place. Make sure to place the ribbons as pictured so they don't get mangled.
Here are how the cables should be ran. Both the black boxes can be zip tied together and placed to the right and under of the steering wheel. You'll likely need to remove the foam piece this next photo is pointing at in order to fit back. It serves no real purpose, it will not introduce any more noise or vibrations.
Connect the other end of the flat cable now to the port on the end of the box according the photo
Find a suitable place under your dash to securely mount the both with zip ties or tape.
Plug in the power cord into the power port as shown on the image above.
Run the other end of the power cord (red) as shown to the fuse panel. You'll remove the specifically pictured fuse, which is a switched fuse, place the fuse you just removed into the empty fuse slot on the provided splitter. Now plug the fuse splitter into the fuse slot you just pulled the fuse from. This is the only fuse I'm aware of here that is a switched fuse. So make sure to use this one. Then find a place to attach the black ground wire to. Suitable places are usually any metal bolt that is connected to a metal frame of sorts.
Optionally, plug in the provided USB extension cord to one of the blue USB connectors and run the other end to somewhere you can access after driving to download your logs to the provided USB stick.
Test, when you turn on your car ignition, your bTres should come on after 30-60 seconds. If it comes on, you are likely done and ready to put everything back and enjoy. You may have some codes that you'll need to reset using bTres or ds1 web interface afterwards.