Just tried with v. 3.5.1
Didn't help.
I red somewhere that it can be because of moodledata cach files... https://stackoverflow.com/questions/24328012/moodle-installation-blank-page-returned
Any other idea?
Thanks
Dejan
Try to clear the cache via cli (php /path/to/your/moodle/admin/cli/purge_caches.php)
Remember to use PHP version 7.1 for the upgrade process from 3.3 to 3.5 and first AFTER the upgrade is finished successfully, use PHP 7.2 (only moodle version above 3.4 supports PHP 7.2).
This method worked for me when upgrading from moodle 3.3 to 3.5
Did you check your web server's error log (like I suggested)?