Am radio loss of reception.

[Tom Denny]

I have lost the am radio reception in my 2016 BMW e89 Z4. FM, satellite, and tap deck continue to function. The fender antenna rod confirmed good by substitution. Any suggestions on where the trouble might be would be appreciated. I have not checked the antenna base or any amplifiers. Also, will removing the trunk interior panels allow access to the antenna base or antenna amplifier if there is one. Does the am signal pass through the diversity amplifier? Hard to find meaningful information on this subject. Thanks for your help.