Upgrade AWS to 1.8.1 failed

I just attempted to upgrade 1.7.8 to 1.8.1 trying to solve an email problem with the Dreamfactory packaged AMI. I used the “upgrade” button in the admin interface at first, but I just got routed to a blank page - and no pages were responding.
I SSH’d to my AMI and ran the upgrade instructions at https://github.com/dreamfactorysoftware/dsp-core/wiki/Product-Upgrades
I’ve also tried going to my AMI’s public DNS/web/logout, as well as curl localhost:80/web/logout, all with no content returned.
I’m still only ever getting a blank, contentless page. When I’m looking, I’m not seeing any overt errors in the apache 2 logs, the PHP logs, or anywhere else I can find.

Luckily this is an early dev instance so if I need to blow it away that’s OK - but I figure this is an opportunity to learn about the recovery process. Any ideas?

As additional info, I successfully started a NEW instance of dreamfactory in AWS and upgraded it first thing with the instructions at https://github.com/dreamfactorysoftware/dsp-core/wiki/Product-Upgrades. I encountered a couple minor problems running the composer.phar update.
One, had to sudo most commands, no problem there.
Two, these files did not exist

cp ../htdocs.old/scripts/installer.sh ./scripts/
cp ../htdocs.old/web/.htaccess ./web/
cp ../htdocs.old/web/themes/classic/views/.htaccess  ./web/themes/classic/views/

Three, I had to edit the /opt/bitnami/php/etc/php.ini file to set the memory limit to -1 from 128mb, as the composer.phar ran out of memory when trying to update.

Other than that, it went smoothly enough!

I’m still hoping to recover my old instance if possible, any feedback would be greatly appreciated.