Switch stuck on JoyCon connect screen

Hello,

i have a problem:

When i slide the Joycons in. I see the red and blue line on the screen. But the Switch stuck on the white JoyCon connect screen. Both Joycons make noise when i touch the button. In the recovery mode it shows that are only the left joycon in the slieder. The right are grey. I dont understand this because when i slide in, the red line will shows and the “clack” noise.

Whats the problem?

Its the Slider broken?

The JoyCons are 100% working.