help to fix my ford 6000 stereo?

Hi, have looked through the site but can't find a problem similar to mine.

My stereo seems to be temperamental. Sometimes it switches on, sometimes it changes to aux or fm etc, sometimes it plays sound although recently it has gave up on this.

I have tried resetting it a few times holding the power button for 15 seconds and this speeds up the stereo operation until the engine is switched off again (and recently it hasn't fixed sound which can come on at random)

Any ideas?