Hello, my name is Mark and I will try help you with this.
You will have to remove the radio again and recheck the wiring.
The radio should have two live feeds going to it. 12v constant live and another 12v ignition live.
The 12v constant live is either missing or has been switched with the ignition live.
Your friend may have also blown a fuse when wiring it back up and this could also be why the central locking now has a problem.
Hey thanks, I was just thinking this site had well and truly scammed me! I have to go out now but will get back on the case this afternoon. I wll be in touch later thanks.
Let me know what you find.