That door trim panel would not be in service in that condition. It doesn't get touched, there's no chance of trolleys banging it and damaging it etc. Although one should imagine the crew do a security search on a cold aircraft, if the aircraft has been sat overnight then a device of some sort could be hidden. It would only need to be very small. Perhaps hidden behind the back row or in an over head. However if it was here then I don't see how shrapnel would make marks on the door as there is a toilet between the cabin and the door.