I found the link to the operation of the 210 shift interlock.

Shift Interlock

The best approach is to get under the dash board and find the Bowden cable that heads toward the center. This cable needs to be disengaged from the brake pedal mechanism and allowed to relax. This drops out the latch lever (item 4 in the pictures) and allows you to shift to N.

If you look at this picture from my evaporator job you can see the cable going into the tunnel through a grommet just ahead of the air bag controller.

https://www.dropbox.com/s/atp58cs35nkr20w/2016-05-19%2012.22.17.jpg?dl=0

I'm pretty sure this detent plate and latch lever are inside the transmission so just unhooking the shifter under the car won't work.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech