Electrical issues are very difficult to diagnose remotely (or locally) and we can only take an educated guess based on our experience....

There is a separate computer called the General Module or the Body Control Module located in the passenger side kick panel that controls the lighting on the car (among other things).  It is possible there is a connectivity issue to this module due to corrosion or moisture.  

Sometimes the software in this module gets corrupted causing strange symptoms like you are experiencing and requires a 'reload' of the software at the MINI dealership to clear things up. This is something we have seen in a number of occasions.

Let us know what you find out!
Ken

I don't know a lot about new MINIs, but in general, it's unlikely that the switch or the bulbs are the problem. Sounds like you've probably got a blown fuse or circuit breaker. 

Hello, 

I need help. I just got a 2003 Mini Cooper base model. The button to brighten or dim the dash was working just fine and now it does nothing and I am sitting in my car in completely darkness as I can’t see how fast I’m going. The warning lights work just fine but the speedometer and things like that don’t. I know nothing about cars or what even could be the problem. 

Also I went to get my vehicle inspected and my lights were working just fine and now my front turn signal lights are not working. Back ones work just fine and I’ve already replaced the bulbs and they still won’t work when they worked just fine 2 hours prior. HELP