I'm not familiar with the Catalina 30, but can't imagine why they would put in an interlock to prevent starting in gear. Having inadvertantly tried to start my engine only slightly in gear a few weeks ago, I can say that the A-4 does not like it at all. It is very hard to start with any load at all.

You should be able to tell if it is in gear or not by hand turning the prop shaft. It will turn fairly easily when of gear.

You don't give enough information for much diagnosis. How was it shut off? If you disconnect the battery it is possible to do cause some electrical problems. Check fuses.

What is the "not starting" symptom? Not cranking? Not firing? It doesn't seem like turning off the ignition in gear would cause any problem but perhaps some more clues would help.