Cd player keeps switching its self on

[Hitchos]

hi all,
for the last 2 weeks or so ive been going out to my car and the sd player has been on luckily hasnt drained the battery, now my cd player dosnt go off when i turn the car off i have to switch it off my self and im one of these who does post flight checks when i stop making sure everything is switched off so i know i havnt left it on any ideas what is causes it to switch its self on?? im having to to take the facia off the cd player just to make sure not a massive thing more of a ball ache