I had an existing installation of Ubuntu 16.04 MATE (unecrypted) and wanted to encrypt my home folder for added security, so I followed this guide.

I followed the guide closely and backed up the account, migrated the home folder using Ecryptfs, created an encryption passphrase, etc. But afterwards, when I rebooted the system, I was unable to log back into the encrypted account. I just got the dreaded 'login loop'. Luckily, I had, however, created another administrator account which I can still log into.

How best can I recover this encrypted user account?

Are any of the following possible:

1. Work out what is causing the login loop and how to get past it;
2. Undo the encryption on the account and log back into it;
3. Extract all my old home folder and application settings from the backup (or the encrypted account?) and copy them into the new administrator account, effectively creating a duplicate of my old unecrypted account. Then erase the encrypted account.

I'd very much appreciate any help.