Inspiron 17 7786 (from 2018)/Win 11: Suddenly keyboard lag approximately 5s/How to get the Service-Tag etc.

Hello and greetings from a German guy,

notebook not usable anymore, (internal) keyboard lag approximately 5s. Starting with Pin input.
Same problem with external USB-Keyboard.

And the Service-Tag/Serial Number/Express-Servicecode/Manufacturer Date on the label is not readable anymore!
So I can't get support from Dell.