Why didn't the Drush command bam-restore work? I'm a new admin of a Drupal site (core 7.38 on an OpenSUSE 11 server). Yesterday I ran Drush up to update VBO to 7.x-3.3 and suddenly I could no longer access the site. The homepage displayed the site's header/logo with the generic error message "The website encountered an unexpected error. Please try again later." I tried accessing /?q=user and some of the other pages via their clean URLs, but nothing worked. 
The server was working fine and I was able to access the tar.gz archive created that morning through the Backup &amp; Migrate module. So I followed instructions I found online for restoring from a Backup &amp; Migrate archive (using bam-restore) but it failed. Drushcommands.com says bam-restore accepts three arguments: source, destination, backup id. I entered the parameters but got another ambiguous error message. Subsequently I found different instructions that avoided the bam-restore command and opted for mysql commands.

Why didn't the bam-restore work?
 Is there a way to get more specific error message or access what's actually going on with Drush in a specific circumstance?
First, I would have run drush up drupal, updates only Drupal core, no third party themes or modules. To do a restore, try drush archive-restore