Did you fix DB issues? May as well do it now. But don't think those DB issues relate to 403 errors.
The 403 in logs indicate 'access denied'. Check ownerships/permissions on all folders/files in code and on a folders/files in moodledata.
Code .... readable by all but writable only by owner group readable should be ok - that owner is the web service user.
Data directory .... needs it all.
'spirit of sharing', Ken