W211 E500 interior lights flashing
 

2005 E500 4Matic wagon:
When I open the front door (either drive or passenger, doesn't matter), the courtesy lights (under the door, dome light) come on for a brief second then shut off. Every ten seconds or so, they flash once. The sunroof will only move about an inch with each press of the sunroof button. The flashing stops, and the sunroof works almost normally with the engine running. This problem does not occur with the rear cargo area lights (after opening the hatch), or with the rear seat lights when opening a rear door. This issue came on suddenly. I have replaced the aux battery thinking that was the problem. Anyone have any ideas, or had this problem before?
Thanks in advance.

FWIW, the aux battery is only for the SBC brake system. Sounds like you have a failing OCP, overhead control panel.