siemens warming drawer

Hi. we have a siemens B1630CNS1B/02 warming drawer with the light flashing. We fitted a new coupling between the drawer and main body which usually cures this fault but the light is still flashing and it is not heating still.. i tested for continuity on the wiring on the back of the drawer (bowl) and there is no reading through it. I’m not quite sure but i thought the glass bottom of the drawer had some sort of heating element in it to create heat. can anyone verify this please or have any more info.
thanks Mark.