park sensors

I'm in need for some help. My regular car is a 2009 Ford Mondeo wagon. It has park sensor, but today and as soon as I put her in reverse, the park sensor button starts to blink and producing this obnoxious sound as if I'm to close to something. I already verified there is nothing wrong with the sensors and already tried to put the car without current to reset them, but nothing works.

The garage is closed right now, but this sound is just soooo obnoxious.

Thanks

Yves