Windows Activation Issues After Updating Motherboard Bios

Question

I recently got a new PC capable of running Windows 11 and utilised the free upgrade from 10 to activate the OS, saying that I'd changed hardware, and selected the previous Windows 10 PC, which successfully activated 11.

Said PC was going without issue for almost 2 weeks after completion and swapping over, but after the Gigabyte Control Centre (I have a Z790 UD AC Motherboard) started causing a Wifi Driver Installation Driver_IRQL_Not_Less_or_equal Bluescreen (Rtf64X64.sys), not allowing for control over fans, and also keeping the RGB lighting of my memory on while the PC itself was in hibernation mode, alongside saying Memory Integrity needed to be off to do things. In addition, the Windows Security Centre started telling me "Local Security Authority Protection" wasn't on, yet didn't give me a toggle even after manual updating was done via PowerShell. Reaching out to a PC repair person friend, I was told to try updating the motherboard Bios and seeing if that fixed anything.

As such, I went off to transfer the F5C Bios (I was on F2 Drivers beforehand) file to a USB (Which admittedly was registering first as a disc drive, rather than storage, and only registered as the correct type after swapping USB ports on the PC), Q-Flashed after a restart, and updated things from there. After going off for a bit and coming back to find my PC had automatically gone into Hibernation, I reawakened it and got a notification saying that Windows was not activated.

Going to the Activation Settings pane, I determined that this was not another bug, and that it was giving me a 0x803FABC3 error code. I thus launched the troubleshooter and was told "We weren't able to Activate Windows on this device". Thinking it may be getting the signal my hardware had changed, I went to "I changed Hardware on this device recently", and selected the Windows 11 PC, because it was the same device I was using. Alas, doing so only told me "Unable to activate Windows: We can’t activate your copy of Windows as the digital license for this device has already been used to reactivate Windows."

Thinking something may have been somehow corrupted, I ran the Source File Checker, which did find some things had been corrupted for unknown reasons, and restarted. This removed the watermark, yes, but it still said Windows was unactive. Coming back today, I once again had the watermark, and nothing had been fixed as far as registration went. Given the short time said watermark was present yesterday already interfered with things, I grabbed a Windows 11 boot drive, and did a full PC format, and reinstall.

While this fixed the software issues, I was at first told that no key was present, and tried to enter the windows 10 key (I've no clue if it changed when activating Windows 11, as I didn't think to check on the grounds I never thought I'd need it again), only to get an error. Unfortunately, this then cycled right back to the previous 0x803FABC3 error, and neither device listed in the "changed hardware" window gave anything outside of the "unable to activate windows" prompt.

Does anybody know why this is happening, and how I may go about remedying it? I unfortunately also never thought to link my Microsoft account with the key, so while I have both an account, and the windows 10 key used to upgrade to windows 11, the only way I've found to link that is via the Activation Settings once it's already been activated. Thank you in advance for any responses given, as I've no idea what else to try fix-wise outside of asking an expert.

Update: the error code has since gone from 0x803FABC3 to 0x803FABBD.