Rear radio control not working

I have a grandeur HG300 2012 (korean version). from the armrest of the rear seat you can control the front radio (on/off, volume, mode, mute, etc..) and the rear seat heat control.
sudently I can not control the radio fuctions from the rear seat ARMREST control unit but I can control the rear seat heat which are all together. all botons (radio and heated seat) are iluminated thus I asume this control is getting power from the vehicle, however radio controls do not work.

ALL vehicles instrucion odometer, radio, BT, etc are in korean language, I was wondering that perhaps there is a boton in the main radio unit (front) on which you can activate or deactivate rear radio control like other vehicles ?
Since I do not know to much korean, perhaps I pressed this boton by mistake..

Could you please let me know if this boton exist..? if not, what could be the problem since this control were working yesterday..
Problem arise after I took my vehicle to the carwash for washing the seats, they already checked all cables and connection, everything is in order

thanks for your help !