DELL XPS 15 9560 BIOS flash update doesnt work

Hi,

i want to update the BIOS on my DELL XPS 15 9560 from v.1.23.1 to 1.24.0 but it doesnt work.

I tried both:

1. starting the .exe file in windows

and

2. flashing the bios after pressing F12 during boot procedure and try to flash "manually" - but it doesnt work. The dell Logo appears as usual, than it disapears for some seconds as if it would flash the bios, but suddenly it comes back and windows starts booting without any changes.

Does anybody has an idea, what the problem could be?

Thanks in advance

Alex