24H2 update - running out of ideas.

It sounds like a unfortunate problem. 

Do not panic.

As Mousefluff said bitlocker is on, by default, when you sign in your pc with your microsoft account.

If you are sure about a clean Install, these steps can be taken:

Press SHIFT + FN + F10 in windows setup installation for cmd.exe.

After type in this in cmd: 

diskpart lis disk sel disk <disk number> clean

I think this should be enough to clean your disk...

If that didn't work then:

Go to your microsoft account on any accessible pc.

Login to your acount.

Go to https://account.microsoft.com/devices/recoverykey

Then see your recovery key...

Now, in the Windows PreInstallation Environment:

Press SHIFT + F10 for cmd.exe

Now type:

manage-bde -unlock C: -RecoveryPassword <Recovery-Key>

This should work.

Hope this helps.