There were two Joomla installations. After updating, both the installations broke and were not working. It seems that the problem was that after updating, the Maria DB server failed to start on its own and it started after manually starting it.
Now, one Joomla installation works and the other does not.
There’s one more issue - I am able to locate the DB of the Joomla installation that does not work. However, the I am not able to locate the DB of the Joomla installation that works!