Prestashop version? php version? can u access BO? Also can u run it on localhost a test there?
- try https://www.templatemonster.com/help/how-to-enable-debug-mode-display-errors-in-prestashop-1-7.html if are able to receive some others errors too, that might lead the way
what did u try/do so far?
Are u on shared hosting or ?