Need someone who really knows what they are doing with phplist. It was working fine until I got someone to fix a PHP version problem with the opencart website (website running on 5.4.45 but opencart version was using 5.2).
After that fix, PHPlist worked but the plugins would not load and I could not get the CK Editor to work so only plain text emails could be written.
To solve this I did the whole manual upgrade from 3.1 to 3.6.5. I followed all the steps to the letter and double-checked that nothing was missed, but now I get a blank screen when trying to login.
I only want to do this if it is quick fix ($50 - $100), as otherwise it's not worth it and I will just reinstall using the CPanel software installer.