I did some searching but did not find any recent info on how the 4matic should work. Indications are that the brakes should be applied to any spinning wheel to allow power to route to the one/s that are not turning?

The situation;
2002 e class 4matic that slid off our driveway into the woods. It had gotten stuck on the steep section so swmbo parked it. Then with no one in it, it slid off the driveway into the woods.

I dug out the snow around the wheels and tried to move it. It didn't go anywhere and the rear drivers wheel was spinning - none of the others were spinning, and one fron wheel was on the pavement. With the wheel spinning the triangle lit up on the dash but I didn't have any evidence of brakes being applied to spinning wheels so the ones not spinning could try to turn.

No malfunctions flashed up on the dash.

So my question is should the 4matic have allowed one wheel to spin? I know that the car may not have been able to pull itself out of the situation it wound up in but it seems like the 4matic is not necessarily working as it should.

Any easy way to test the proper functioning of the system. Car is still under the extended warranty.

Thanks for any help.
Paul