Trying to clean install Windows 11 - stuck in a BIOS loop using Windows Media Creation Tool, Rufus says FAILS at Security Validation step, Ventoy simply gives Security Error message

Hello!

I'm trying to reinstall Windows 11 on my computer. So far, I've managed to delete the previous Windows partition on my SSD, but failed to install Windows yet.

I've tried two methods:

1. Using Windows Media Creation Tool. I have to main issues for this step. Using the Default Bios settings, I do see the USB as an UEFI bootable option, but whenever I select it, it brings me back to the Bios itself. It's an infinite loop. However, if I somewhy disable Secure Boot option, then it boots, but the installation can't proceed because it says Secure Boot is required.
2. I tried using Rufus. I can create a bootable USB, however, I can't get to the Windows installation window, it always stop at a list of checkups where it ends with "FAILURE: bootmgr has encountered a security validation or internal error". Disabling or enabling Secure Boot makes no change. I tried two distinct ISO: one on the official Windows website, the other created from the WMCT. I could never choose the "Fat32" option on Rufus, which has been mentioned as a possible solution, but it simply never shows even if I go in advanced options. I tried with and without the "remove secure boot necessity", no change, still the same security validation message.

I have an Asus motherboard, the whole PC is pretty recent (2025). The Bios update is from 2025.

I tried Ventoy. It "boots", but not to the Windows installation either, it just says "security error"

Finally I tried changing "Fast boot" from Enable to Disable, then I did reset the Security Key and loaded the default ones. No change. CMS is disabled.

I'm out of luck. What am I missing?

Thank you!