Problem During Upgrade

I ran into an issue during an upgrade from Expression Engine 2 to Expression Engine 3. I read through the upgrade information, copied the new directories, set permissions as specified in the upgrade documentation. I then went to the admin.php page on my site and started the upgrade. Everything was progressing OK until I got the error message about the missing avatar_path in the config file. I followed the instructions and added the missing path and attempted to run the admin.php file again to upgrade. I now get an http 500 error, server busy page. I put back my old directories which brought my website back but now I can’t login to the expression engine 2 as any of my members or the admin user. It appears something happened during the upgrade but I don’t know how to fix it.