2016 bmw e89 z4. Have lost am radio reception. Fm reception, satellite reception and tape deck still function. The fender rod antenna appears to be good by substitution. Don’t know if there is an amplifier in the antenna base or another amplifier for the antenna. Don’t know if it’s true or not that the diversity amplifier is only for fm. Any suggestions regarding the problem would be appreciated. Also can the antenna base be accessed by removing the trunk inner panels.