what matrix are you referring to?
The matrix that indicates faults with the car ie. release the footbrake. At the moment certain parts of the message do not show.
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this is a common problem, the LCD panel is failing
the best fix is to send out the unit for repair, any of the other fixes you read about online are risky and likely to be less than permanent
here are options for such a repair service: http://www.clusterrepairsuk.co.uk/featured/bmw-instrument-cluster-lcd-pixel-repair and also http://www.speedofixer.co.uk/pixels.html
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