2003 530 radio

The 2003 E60 BMW cars operate on a Media Oriented Systems Transport bus or MOST bus and there could have been a connection that was disturbed in the process of changing the battery. I used to work with someone that was very much against people working on their own cars due to the possibility that they did not know what they were doing and could cause trouble for the repairing technician, even when changing a light bulb, which is of course somewhat silly. This may be one of those cases, the optical "plumbing" can be sensitive to rough handling and if this is the case, you may need to set an appointment with your BMW service provider. If my guess is wrong, there is still very little you as a layperson could do about it as the sophistication of the car does not lend itself to be easily repaired by the end user. Perhaps there is a software concern or an actual module in the MOST bus that was borderline and the replacement of the battery pushed it over the line.