I have a Grundig Model GKN16910B and a warning which I cannot clear has begun flashing on the control panel. The freezer temperature flashes with the letter "E". I have checked that the door is closing correctly and no new or warm items have recently been placed in the freezer compartment. I have noticed that there does appear to be a build-up of ice behind the back panel of the freezer compartment which has caused the back panel to bow. I have set the freezer to emergency freeze. Any help or advice would be greatly appreciated.