Volvo HU-603 audio does not turn on panel lights.

A client has brought me the HU-603 Audio team of Volvo because they do not light the lamps of the front panel (removable) says that it happened to him after a sharp bump. All lamps are ok. In Volvo's electrical scheme it appears that the current reaches PIN 1 and PIN 2 through accessories. But I think there must be another connection since everything works but without lights. The LCD panel also works and its lighting is fine ... I lost myself ...