Urgent: cPanel Database Connection Error After Attempting Server Optimization - Why is This Happening?

Just hit a critical wall trying to implement some server management and optimization techniques for our website, and now our cPanel database connection is completely broken. Keep getting this persistent error:

[2024-07-29 14:35:01] ERROR: SQLSTATE[HY000] [2002] Connection refused
Failed to connect to MySQL database.

What could be causing this immediate connection refusal after server optimization, and how can I fix it urgently? Thanks in advance!