It sounds strange because the unmodified radiusd.conf does not have authentication, authorization or accounting enabled for sql. I followed your instructions, and rlm_sql_mysql is not started because it has not enabled in radiusd.conf.
You're correct. I copied files I thought were an original, but had already been modified.
How is your working radiusd.conf looks like in the following sections :
- - authorize - - authenticate - - preacct - - accounting - - session
This time I did copy the original files over to raddb dir. I then modified sql.conf and changed the username/password to match my user. I then opened radiusd.conf and uncommented every instance of sql. Then I fired it up and it started fine and made the 5 sql connections. No need for me to post the configs because they are exactly the same as out of the box, except that I uncommented sql in authorize, accounting, session, and post-auth. I have no idea what could be wrong at this point. What version of mysql are you running? Can you start mysql and query it from the command line?