I was just struggling with the blank screen problem during a moodle installation.
Turns out that Red Hat's distribution of PHP has error logging disabled by default, which is why you see blank screens instead of error messages. This is also why you see no error information in the logs.
When you are installing moodle, be sure that php.ini has the following options set to On:
- display_errors
- log_erros
- display_startup_errors
This helped me a lot.