If you setup a Dreampress installation with a *.dreamhosters.com temp site.
And when you deploy the final domain the links get stuck to the old .dreamhosters.com, including the admin area which becomes unreachable.

Make sure wp-config database credentials are directly reachable (or they evaluate correctly for a command line script).

SSH into the host and clear Varnish and Memcached caches:
curl -X PURGE “http://yourwebsite.com/.*” ; wp cache flush

Also, you may want to temporarily rename wp-content/object-cache.php, flush, and revert to the correct name.