GLC Rear Window Heating Issue Resolved

I had a similar issue with my BMW 5 series rear defroster and auto defrost. Check the heating coil grid on the rear window for breaks. What's the specific error code? A generic error isn't helpful.

I visually inspected the rear window grid and saw no breaks. I will get the specific error code. Can a small break disable the entire rear window heating? Could this also affect the windshield heating?

Yes, even a small break in the grid can stop the whole rear defroster. Windshield heating is separate, but modern cars are integrated. A voltage drop from the rear window could affect other components. Given the symptoms and no visible damage, plus the battery concern, get a diagnostic check at a workshop. They can test the battery and electrical system.

The workshop confirmed it was the heavily discharged battery. I replaced it for 290€, and the rear window heating now works. Thanks for the help.