If there are multiple drives installed in the computer, then it can create confusion as to which drive has a Bootloader. This scenario usually happens when Master Boot Record is on the wrong drive.
If when you start up your PC you don't see any boot menu at all, you'll need to first learn how to make your GRUB menu appear ...
Earlier this week, Microsoft released a patch to fix a Secure Boot bypass bug used by the BlackLotus bootkit we reported on in March. The original vulnerability, CVE-2022-21894, was patched in January ...