Didnt look to see which car you have, but, to disengauge the lock on the W201 and most W124 cars that I know of is a simple cable system. SO, without electricity is should still work. The brake pedal arm is the mechanism that actuates the cable that allows the lock to disengauge in the shift housing....so...if you remove the valance panels and trim that is under the steer wheel and in the foot well under the dash, you can get at the cable end that lets you release the cable. If you cant just step on the brake and it releases, maybe you can disconnect the brake pedal end of the cable to actuate the cable lock release. I hope this works for your car, I know it works for all W201 190E cars that are 1989 and newer, my 1986 can has no trans shift lock system at all. I can take it to any gear with or without the key. Nice, but easy to steal I guess. I keep her in the garage most the time.
Good luck

__________________
Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red