You likely have a shorted door lock actuator which you can replace with a new unit for the lock that is not working. Perhaps your mercedes locks work but they open and close slowly. If a door unlocks but will not lock again then replace the door switch.
Dptool Engine Camshaft Alignment Timing Tool Kit For Bmw Mini Copper N12 N14 1 4 1 6 Citroen Peugeot Engines Car Accessories Online Market In 2020 Mini Copper Bmw Peugeot