26H1 has no upgrade path and is based on a different Windows core than 24H2 or 25H2.
https://support.microsoft.com/en-us/topic/windows-11-version-26h1-6a0533a9-71a8-43b8-a32c-8fa7db97543d
26H1 is not a direct upgrade path from 25H2.
26H1 cannot be updated to 26H2.
The path from 25H2 is 26H2 but it is not available yet.
https://support.microsoft.com/en-us/topic/windows-11-version-26h1-6a0533a9-71a8-43b8-a32c-8fa7db97543d
When I was using Macrium and had revoked the 2011 cert I found I could update the rescue media using this command and no more SVN mismatch error at boot.
May need to change drive letter from F: if yours is different.
copy C:\Windows\Boot\EFI_EX\bootmgfw_EX.efi F:\EFI\boot\bootx64.efi
I normally just hold down the Windows key then press L to lock the computer.
I tried what you wrote but pressing enter twice on the lock screen just showed my password hint.