Corsa d radio not working

[Nads02]

A mate of mine has a corsa 2009 1.4 petrol. He left It parked for a while and found the battery flat. He decided to jump start it but ended up connecting the jump leads to the wrong terminals 🙃. He said there was a big spark and he took it off straightaway. Eventually he got the car to start but the radio stopped working after that. Also the battery would need a jumpstart every single day. So I replaced the battery for him (labour charge was a cup of tea and digestive biscuits) and the car starts and drives fine now, but the radio still isn't working. I checked the fuses behind the glovebox and they seem fine, but I still replaced the fuses just in case and it's made no difference. I spoke to an MOT man whilst I saw him outside the garage, and he told me there's a fuse behind the radio? I'm not too sure but that doesn't seem right to me. I asked one of my college mates and he said to disconnect and reconnect the battery, could that work? How should I get the radio working again so we can play kiss fm?

[Brian_996TT]

did you check the fuses under the bonnet

[Nads02]

https://fusesdiagram.com/opel-vauxhall/fuses-and-r...

I used that to help me out but didn't check the fuses under the bonnet. Which fuse would it be? The orange glow that you get on the radio buttons when you turn on the headlights don't turn on as well, which confuses me even more.

[Brian_996TT]

there must be a fuse that protects the power to the interior

[Paulomint]

I have the same problem with my radio, I replaced the fuse behind the radio but I guess it is shortcircuited because the fuse
... Fused. Or I tryed a used fuse which I don't think so. How did you solve it on you end?