Recently the battery of my car ran down to flat and after charging and reconnecting it, my audio unit will switch on and off but only limited functions work. ie. music on USB stick will play but no other functions work, no paging or track change, not even the volume operates. CD's will play sometimes but only after ejecting and re-inserting but again, no other functions will work. I have tried the re-set button but it makes no difference. Does anyone know if the unit is repairable or is it up the swanny? I miss my in car music so much it hurts. Thanks in anticipation.