Overvoltage relay on that car is at the RR area of the engine compartment.
There is a black plastic door that lifts from the front, the ovpr is there.

MB 000-540-67-45 is the replacement number.

Do the red/green lights(mirror) flash while you are cranking the starter?

If they do?, you need to try locking/unlocking the central locking system several times with the remote key.

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