Alright, I've read a number of threads about updating JMS and the "recommendation" is to uninstall patches before attempting to update JMS or any core Joomla files.

I've intended to update to the latest version of JMS and have uninstalled the patches to start the process, but now my whole site is down immediately after uninstalling these patches.

So, please tell me what I can do to 1) restore my site functionality and 2) update Joomla or JMS without having to go through a nightmare of site outages.

When you uninstall the patches, this restore the original files that was backed up when installing the patches.

If you have a problem to acces the master website, this mean that you have modified the connection to its DB (for example the DB prefix).
It is normal that all the slave sites are not available when you have uninstall the patches.

If you have a backup, verify you "configuration.php" file located in the master root directory. Perhaps you have a different DB connection parameter and table prefix.

After searching more threads - this one actually helped - www.jms2win.com/en/forum/23-general-ques...87-site-upgrade#4087

Since the old configuration.php file you have upon installing JMS is saved and restored upon uninstalling the patches, you need to ensure your configuration.php contains current information.

In my case, the configuration file had the incorrect information from over 3 months ago when I initially installed JMS.

Little details like this would be very helpful to include on JMS documentation since this is an issue that is quite common.

Unfortunately, I spoke too soon...

After restoring the configuration.php file to it's operational state - I could access the front-end of the site, so that is definitely a step in the right direction, however - I cannot access the back-end administration panel.

This should be interesting...