hey there,
Thanks for getting back to us quickly, I've checked in your site, it seems like when you open backend > system > global configuration page also hitting 500 error, then I found out you actually hitting this error :
Parse error: syntax error, unexpected '?>', expecting function (T_FUNCTION) in /home/chuwarba/public_html/libraries/legacy/request/request.php on line 281
It seems like you this file is not updated, I have replace my local file into your site, it should work fine now, can you give it a check now?