FileVault locking HDD

When I try to log in the text field shakes indicating a wrong password - the same thing happens when trying the recovery key.

I can unlock the volume in Disk Utility more specifically it does not ask for a password there nor does it show any encryption which makes sense since the problem happens after activating FileVault when there is no encryption in place. Although the backup used to restore the system is from a system that had FileVault activated.

A firmware password has not been set.

The backup I used is just one day old. I did a complete backup via TimeMachine before reinstalling.

Sorry I was pretty busy and have not been able to test it yet. Will post as soon as I have time to try it out.

Output from diskutil cs list in recovery mode as well as normal mode is:

No CoreStorage logical volume groups found

I deleted the whole Macintosh HD and did a fresh reinstall. Afterwards I just copied the applications from my latest TimeMachine backup and did some configurations. Trying to enable FileVault resulted in the same problem described in my first post - neither password nor recovery key unlock the system.

In Recovery Mode diskutil cs list now outputs:

Encryption Status: Locked

Encryption Type: AES-XTS

Conversin Status: Pending

Conversion Direction: -none-

Has Encrypted Extents: No

Fully Secure: No

Passphrase Required: Yes

.....

Size (Converted). -none-

Revertible: Yes(no decryption required)

I think I once came across a similiar bug after uninstalling an encrypted linux system. There seemed to be sone artifacts left on the hdd which I was only able to delete with a special tool.

Is there a way to activate FileVault from the point I am now or at least a way to regain system access without doing a full recovery?

Furthermore I m unable to boot into Single User Mode voa CMD+S. It appears to be loading for a short time without displaying an explicit error but then it just reverts back to the standard OSX login screen.

I am really disaapointed with the problems in hardware and software in apple products of late as I have including mine three cases in my family with a brand new iMac and MBPr with severe Hardware problems.

They used to roll out new features when they were ready not when they where still as buggy as they are today.

I now tried to reset the password via the recovery terminal using resetpassword. Unfortunately the problem still persists and I am unable to login.

I will try to deactivate the outstanding encryption next and reset the password again and hope I can log in afterwards.

Though the goal still remains to reactivate FileVault....

I was able to regain access to the system deleting /var/db/.AppleSetupDone and then executing diskutil revert disk.

After that a I was able to create a new admin account.

After activating FileVault again I was now able to login and the encryption is in progress.

Apparently the diskutil revert disk did the trick - thanks for the help hope someone else finds the solution useful.