No bootable devices found (XPS 15 9550)

Hi,

After installing Windows Creators edition and also some last Dell updates I am not able to enter my laptop anymore. I receive the message "no bootable devices found".

I have an XPS 15 9550

System BIOS: 1.2.25

I tried via F2 to check if secure boot option is enabled : Yes

I did Diagnostics Test and no issues found

How to fix this problem?

Thanks and regards,

Rene