Started car remotely. Car shut off after 3-5 seconds and horn soundedNow won't start

Sounds like some kind of anti-theft feature that is kicking in due to the car thinking someone is getting in without the key. It's too hard to know without having a diagnostic tool hooked up to see what may be triggering the event. Also, are there any non-factory devices added onto the vehicle? www.repairpal.com/repair-shops