Hello. I have installed ispconfig in stable version. 3.0.5.4 - I have got a lot of mysql errors, before it I had got problems with permissions to config (anyway) After it, I installed beta release, I fix problem with socket to php-fpm (Now I'm using 7.0 version not 5.0 as ispconfig want), and have login screen. After pass valid data, it goes nothing - no errors, only page reloads. If I pass wrong data I see password error.
Seems as if you did not follow the installation instructions (perfect server guides) which instruct you in detail which MySQL version and PHP version for a specific os has to be installed. Installing other versions will likely cause a broken system as you found out yourself now. To fix your server, format it, then reinstall it by following the installation instructions in the perfect server guide.