Nice car.

On w211 the wiring along the left side of the trunk lid tends to break from repeated opening and closing. You have to dive into the wiring harness and patch up any broken wires. This is frequently why the trunk won’t remote open. I think you’ve got more going on than that, but it’s a place to start.

You might try looking for information in the w211 forum over at mbworld. There’s a lot more action on the newer models than here at PP.