I have one of these cars and having had the headunit out a few times i'm sure there is no inline fuse iirc there is no fuse at the back of them either.
Unlikely your friend has a voltmeter but if they do it would make life much simpler if you could just check to see if it is getting any power. Try switching on manually and with the ignition as they are both fused seperatly.
hi, tidy clio. thanks for the info m8. we found the problem. the fuse [main box] was blown. on the very end. hard to see, as we always look at the middle bit. put in the code, & its working ok . cheers m8. p.s. you are right. no in line fuse. thanks again. good forum this.