Sounds like the bottom drawer thinks it is still open. On the side of the main control board there is two light sensors & a prism lense. Light from one sensor is bent through the prism into the other sensor when drawer is closed & lined up correctly. Either the prism is broken, the light sensor is not working or the plastic mounting case is broken putting the light beam out of line. If you don't know where all this is or what I mean get someone in to check it or else you may end up damaging the control board.
Lincoln Appliance NZ, April 2010