Nuki Opener - Bluetooth connection failed

Hi,
I have a problem with reinstalling my Nuki-Opener. Before the reinstallation process I deleted the device from the web and ios application. Then I tried to connect via Bluetooth and it failed. I pushed the button 5 sec down nothing happened, after 10 sec I am in maintenance mode ( led is blinking every sec.)

I also tried to remove the batteries and reinsert them, push the button 5 sec. down. Same problem and I cannot get into bluetooth pairing mode.

Do somebody know how to do a hardware reset without app connection? Or have somebody the same problem?

I am very thankful for any help and advice.

Greeting
Florian

Have you found a soulition? Having the same problem