Radio won't turn on

Hello there,

This is my first post/question here and I hope it's the right place for it:

I own a 2007 Chevrolet Epica, 2.0, 150HP. I've bought it recently and
everything is working fine except the radio which won't turn on no matter
what I do. Before, I could start it from the steering wheel or directly from its
own power button but now it seems dead... I checked the fuse from the
drive's panel but it's not blown. The radio doesn't have a fuse in the back.
The weird part is that even if the screen is black and there's no sound or
response when pressing the power buttons, the buttons still have light/power
if I switch the high beams on for example.

Any ideas about what could be wrong with it? I didn't find a lot of infos about
my car, I almost feel like I've bought something kinda rare