BMW E61 rear glass won't open (no power) 

The BMW E61 tailgate is one of the most problematic automotive devices ever produced, and almost every repair begins with getting the rear glass open.
This is the easiest way that I've found to get a malfunctioning rear glass open on an E61.
You'll need to drill a hole through the plastic tailgate panel. Don't worry, it won't show.
I used a 1 3/8" hole saw to make the hole, just to the right of the left elastic band.
Tear out any foam you encounter behind the new hole, and you'll be able to see the window latch assembly.
The distance from the plastic panel to the latch release is 3 3/8" (86mm), so your average Allen wrench won't be long enough to reach. I made my own tool out of a piece of steel rod. The business end of the rod has been ground down to slightly below 1/8" (3 mm). I rounded the tip, so it slides into the latch easily.
This is just the beginning of your tailgate repair journey. Safe travels!