Hi, I own a 2009 a3 with the symphony head unit with BOSE speakers . The stereo (when turning on the ignition/starting the car or manually pressing the power button on the head unit) only powered on sometimes it was a gamble on wether it could come on and turning on/off the ignition to try and turn it on wouldn't help it either. So I bought some key removal tools and went and got a replacement 10A fuse from halfords for the bak of the head unit to see if that was the problem and at first after replacing it, it was working (made a disk eject like noise on plugging back in, i don't know if that is normal) although that night when I went back in the car i had noticed it wouldn't come on again so I remove the stereo again and plug it back in and it works again all night after turning off and leaving the car a couple of times until the morning after and the problem is back with it not powering on, if anybody can please offer any help ill be very grateful as its making me want to tear my hair out. And sorry about the long paragraph just wanted to explain everything...