Any help with this would be appreciated, but before we suggest, take it out and have a look, ask the dealer who sold it, ask blaupunkt, quick history.
It's in a mates 91 BMW 318 now he had a prang, got severly F#@##ed around by panelbeater (4 months to replace rear quarter panel). They left metal swarf all over speaker terminals and HU went pop when turned on. Insurance replaced it with the CD35 after much arguing and the installer is not helping at all.

Symptom
When the unit is first turned on,the unit makes a noise like a cd being loaded, HU initialising, just for a couple of seconds. When he queried this with the installer he was told these units have an inbuilt fan for cooling and that's what the noise is, my opinion cough bullsh#t cough. The installer hasn't actually listened to it. He also didn't get the removal tools or installation diagrams which doesn't help.
My initial thought is the battery/memory wire (yel) has not been put to a constantly live circuit however the HU has a feature where it can be turned on without the need for the ign to be on.

Question
Does anyone have one of these units or know much about them?
Do they have an inbuilt fan?
Do these decks initialise the cd player when first powered up?
Do the use the batt wire for the pwr up function with ign off or is there another wire for this?

Thanks

Some Blaupunkt Decks do make a Turn on Noise and initialise the CD Player..
It Depends on if the Deck is Not Playing or messing up majorly

If he has any doubt take it to an Independant Installer and Have it assessed then he can go back to the original Installer armed with some knowledge

Some Blaupunkt Deck do make a Turn on Noise and initialise the CD Player..
It Depends on if the Deck is Not Playing or messing up majorly
Thanks mate