[SOLVED] Error Reporting / 500 Internal Server Error / VQMOD

I would appreciate some advice on how to diagnose an issue with a previously healthy store running Opencart (2.0.3.1).

The store was working fine until installing VQMOD (from the official site, vqmod.com) Now I receive a 500 Internal Server Error'. The issue may have been caused by my changing file permissions (as per VQMod Video on Youtube - 23/7/15). I installed VQMOD as it is required for the ProductOption Image extension (by LiveOpencart). However, I am at a loss as to how to diagnose the issue.

I have set
display_errors = 1;
error_reporting = E_ALL;
log_errors = 1;
in php.ini (and in index.php as this did not work) but receive only the basic 500 error Internal Server Error Message. No error messages are written to system/error.log I have reloaded the backup for both the public_html directory and database to the server to no avail.

So, other than a clean install is there anything else I can look at to diagnose why my installation of Opencart has become corrupted? (For reference the site is modelscenerysupplies[dot]com).

Thanks.

Update: Have resolved the earlier 500 File Not Found server issue - index.php had excessive permissions. However, am now unable to access the Admin page via the web browser (ie it is not at /admin). Have checked admin/config.php file and it points to correct path. I have even tried moving the Admin files, updating pathReplaces.php of vQmod in accordance with this thread on Admin Folder Changes and vQMod to no avail.

So, if I am unable to view the Admin Login page at the expected file path (as viewable via FTP) how do I reset or find the Opencart admin page? (It isn't the file path in admin/config.php as I have been accessing that without problem prior to installing vQmod)

I'm having the same issue, can access my site but not admin page. Did you resolve this?

Oops, fixed it. Admin also had excessive permissions. Changed back to 755 and it's fine.