First, just to be sure, you have the light switch at the 12-oclock position (Just to be clear). Second, check the rear hatch lower bay under the rug and Styrofoam for water/moisture. The central locking module has a function for the lamps/alarm and when it gets wet all types of stuff happens. IF ANY water damaged that module (even if already dried up), you may be searching for problems for many tries/fails. If stored outside, you have a chance of finding water if you slip some (few sheets) paper between the foam and the metal sides (below the hatch rug). If the car is stored in a garage, it makes sense there may be prior water damage IF you didn't detect any water on the paper. I read a few problems about this a long time ago and proactively bored a hole in the two rubber plugs under the car rear that leads to the hatch area but this doesn't help anything if there is water damage there. IF you don't find water on the paper testing, you might have to remove the trim from both sides of the hatch and the lower rear of the hatch area. Taking out the foam section on the right side, there are two modules located at the right fender well area. Check them carefully for any water damage. It is a lot of work to get into that area if you remove those trim panels. I have heard of some just carefully cutting out the right foam section but the best is to remove the trim and just take it out (to check/inspect for any water intrusion/damage). Others may suggest the lamp control, I see you acquired one already that didn't help, but getting parts without doing some cost free steps is entirely up to you. The only thing I had to pay for removing all the trim (for access) is the MB type clips that are available pretty inexpensively. Good luck, OH, have you downloaded the service manual yet? That might help in troubleshooting or access to how to take the areas apart (that you decide on),


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