I have a 2013 BMW 535i with issues in the radio unit. The iDrive seems to be working just fine along with the radio, but has some problems with features. The car has BMW HiFi System Professional DSP with NBT. Below is a list of issues I'm having...

- Radio does not keep preset radio channels once the car is turned off, then back on again
- Slight clicking noise that lasts for about 15 seconds, stops for 15 seconds, then restarts all over again.
- Bluetooth works for phone calls, however does not allow audio streaming. When trying to play audio from the phone, Bluetooth just says "Loading...". When trying to sync contacts to the car, it also says "Loading..."
- Navigation doesn't work. When selecting Nav on the iDrive controller, it shows a screen "Navigation is starting", but just stays on that screen.
- CD/DVD seems to be able to receive or eject disc

Those are the issues I've found so far. Wondering if this is fixable? Has anyone run into this issue? How did you fix it? I've tried to a reset by pressing the volume knob down for 30 seconds, but doesn't do it. Was thinking of picking up a working used unit and try to have it programmed to my car. Anyone have any experience doing that? Expensive process?