UNPLUG IT FROM THE SUPPLY !!!!
remove the slider knobs which send the plate warmer up and the start switch , prise the blue base at the control end up and away from the base about quarter of an inch.
leave the blue plastic end piece at the control end then slide the brushed aluminium case off away from the control end.
If you are not electrically qualified - leave it alone.!
eddie dodd
August 2013