Dell Precision 5510: BIOS update failing

Hello!

I reinstalled Windows 10 on my Dell Precision 5510 and wanted to install ThunderBolt software for my Dell Docking Station. That failed due to outdated BIOS version. OK, let's update the BIOS! And then a long way of BIOS updating started...

I tried it four different ways:

- via Dell Support Website

- via Dell Support Assist
- via direct executing of the Precision_5510_1.23.0.exe
- via F12 -> BIOS Flash Update -> choosing the downloaded update file, also with the /forceit option

But it doesn't work: I don't get any errors, but the BIOS version remains the same after the reboot:

Windows + R -> msinfo32 -> BIOS Version: Dell Inc. 1.15.0, 23.07.2020

How to solve this issue?

Thx