type cover not working

[wonk]

Hi,
after an update from win8.1 to won10 the type cover is no longer working. Drivers are not installed. I tried the following

• full reboot after enterong BIOS
• reset Win 10
  
• trying to install drivers via system contro
• my type cover works, when put to a new surface 4
• putting a new type cover frpm another surface to my surface: does not work, np drivers are installed, the type cover is not receognized
  
• contacts of my type cover should be ok

What can I do more?
Gruss, wonk