Clinton --

Perhaps you can remove the inner panel even though the door is closed. You might need to pull the rear seat bottom to give you clearance to pop the snaps.

Once the panel is off, you can probably reach in and manually unlock the door.

I've found on my older 240s that the door latch and lock mechanisms gradually gets dry, corroded, rough, balky. In several cases I broke outer door handles because the mechanism was so hard to work.

Now, as a routine, I remove the inner panels on all doors (about once every 3-4 years) and liberally blast oil all over the sliding latch parts. I do this with my oil gun and compressed air. Yes, it drips out of the bottom of the doors for 2-3 days -- but the doors don't rust! But also the latch mechanisms become smooth and functional.