Ian, I had a similar problem with a Global 450 back in 2002 or thereabouts (while it was still under warranty) and a technician completely replaced the microprocessor board. It sits just inside the top of the door and it didn't take him long. As he unplugged each lead from the old board, he immediately plugged it into the new board. Mine is still going strong - I'm about to replace the door seals on it. Steve.
Steve Saunders, July 2009