Today after starting my car, I got a charge malfunction error and my power steering would not work. I looked under the hood and the serpentine belt was hanging. After getting into it, I noticed the tensioner pulley (or at least that's what I assume it is) is very wobbly and loose. However, I can't see a way to get the darn thing off to inspect it or how to tighten it back up. I've searched all over and can't find anything specific to an e60. Any help would be greatly appreciated.

Here's a video:
BMW E60 Loose Pulley - YouTube

 

looks like maybe the main bolt that holds the tensioner on, snapped its head off.