replace the unit....circuit board inside is going bad...don't try to repair...part is 50-100 dollars

 

Essentially I am experiencing a very similar situation but with some alternate circumstances. 2011 Hyundai sonata and the anti theft is disabled bc i got it from an auction and there is no key fob only standard ignition key now. The dummy light is the only functional part of the system. I never had issues with the flashing lights randomly going off ...until today. I just had some work done at a shop and im thinking they inadvertently reconnected the anti theft system, not paying attention to that i had standard key mot fob. there is no sound bc there is no siren and even my horn is aftermarket so it is not connected factory style. This is just my guess and hoping that it is a right guess ...