2011 ForTwo's radio sound working only when handbrake in specific position

Howdy mates, working on my dad's 2001 Smart ForTwo Passion rn and I'm having a small but rather annoying issue. There is currently no sound coming from the radio, UNLESS the handbrake is very slightly pushed to the right. I know it's probably a wire or something, but I started my auto mechanic classes not too long ago so my list of knowledge is small (besides, I know more about classics, so a Smart is something new)

Any of you fine people might know where to start, or atleast can share wiring diagrams and all that?

Cheers