Recognize this sound? Charger says battery is full. Remote door locks work, lights work.Sure sounds like a battery being dragged into the mud by some heavy load.
There's an interlock for the shifter (must be in Park) and (for the NCV3) an electric motor that releases the steering column.
There may also be an interlock with the brake pedal.
Full service documentation:
http://www.diysprinter.co.uk/reference/2007-sprinter-service-information.pdf <-2007 MB service manual
http://www.diysprinter.co.uk/reference/2007-sprinter-wiring-information.pdf <- MB wiring diagram from above
http://www.diysprinter.co.uk/reference/2007_Wiring-sprinter-2500.pdf <-- 3rd party wiring diagrams
Hang a voltmeter on the battery (or dashboard 12v socket) and see what happens...
p.s. before Bobnoxious says it: **check all ground connections** (could be a bad connection from battery to frame ... verify the near-gas-pedal master disconnect is properly seated)
After seeing the video, I'm changing my answer to the electronic steering lock. Do search for the keyword ESL or EIS and you'll find several threads about fixing it. Here's a recent one.It sure does sound like a stuck steering lock... Locate the steering lock underneath the dash and gently tap on it with something.