Help!

Hello everyone! What I was afraid of (battery too weak ), came in. When I wanted to start today, nothing went any more. I now hanged it on the charger and the battery takes on power, BUT: The immobilizer does not stop blinking when I plug in the pen. It continues to flash and a start is not possible. Does anyone have a tip? I can’t go any further. I have to say something about it: above the passenger door, inside, behind the “fear attack” (handling handle ) is a small rosette with a small hole in the middle. There comes out, as soon as the ignition is switched on, a very strange noise, a kind of clatter. It stops when you turn off the ignition again. Could possibly have to do with the central locking. I had often gone after this noise unsuccessfully. Today I found it by accident.