I got this error message says "You have an error in your SQL Syntax
Where do i find upgrade.php and if i execute that, will it cause any further issues?
Ignore the version error, there've been no database changes in 2.0 branch. The syntax error may be due to a poorly configured mariadb implementation.
Maria db requires some manual code changes, depending on the mariadb config...
Incidentally, mariadb is not officially supported in 2.0.x