PLEASE NOTE:
When you click Updater in the Live version of the site running 3.9 the error message below is displayed.

Warning
Failed loading XML file.
Space required after the Public Identifier
SystemLiteral " or ' expected
SYSTEM or PUBLIC, the URI is missing
Opening and ending tag mismatch: hr line 7 and body
Opening and ending tag mismatch: body line 4 and html
Premature end of data in tag html line 2

After checked further on this, it seems like this 3rd party module Social Fancy Sliders caused this issue.

Notice: Use of undefined constant DS - assumed 'DS' in /home/joomla19/public_html/AMPED18/modules/mod_socialfancysliders/mod_socialfancysliders.php on line 15



Warning: require_once(/home/joomla19/public_html/AMPED18/modules/mod_socialfancyslidersDShelper.php): failed to open stream: No such file or directory in /home/joomla19/public_html/AMPED18/modules/mod_socialfancysliders/mod_socialfancysliders.php on line 15



Fatal error: require_once(): Failed opening required '/home/joomla19/public_html/AMPED18/modules/mod_socialfancyslidersDShelper.php' (include_path='.:/usr/php/54/usr/lib64:/usr/php/54/usr/share/pear') in /home/joomla19/public_html/AMPED18/modules/mod_socialfancysliders/mod_socialfancysliders.php on line 15

I already applied some fix in this file JoomlaFolder/modules/mod_socialfancysliders/mod_socialfancysliders.php on your test site, it should work fine now, can you give it a check is it work fine now?

PLEASE NOTE:
When you click Updater in the Live version of the site running 3.9 the error message below is displayed.

Easyblog 3.9 updater no longer work.