2007 Kia Rondo won't start, but lights, radio, etc. work.

have you tried changing the starter?

We too have a 2007 Rondo LX 6Cyl - Occasionally will not turn over.  If you keep at it long enough it eventually will.  We have had a relay in the ignition replaced, starter replaced and it is still doing it.   The dealership we went to is stumped (and not very helpful).  Would like to know if you try anything that works.