Seat (car) radio turns itself on

[tj]

My neighbor have a Seat and the radio turns itself on when the car stands for the night. Does someone have a solution for this.

[torbjorn]

I think you should tell more about the exact model and year of the car as well as of the car radio.

A common problem on many VAG (VW, Audi, Seat, Skoda) cars is that the relay for supplying of all accessories via the ignition key gets unreliable.
You can test this by connecting a temporary wire to the ignition B+ of the radio, when you leave the car for the night, connect it to grund via a weak fuse (0,5 A or so). Next morning, BEFORE you switch ignition on, check if the fuse has blown during night. If so, then you know that the problem is in the accessory relay or in the ignition switch.