2015 Prius C, horn blaring and doesn't stop when driving

Hello All,

This is my first post here, but I am getting frustrated with my 2015 Prius C. Recently, I parked my car and went to lock it with the key fob (physical key) and when I locked the door the horn started blaring. Thought it was a door not being closed properly so checked that, checked door latches/switches no apparent issue there and eventually the horn/alarm stopped on its own. When I got back in the car no issue but when I got out and got back in again, upon unlocking the car the horn started again and this time it didn't stop even when driving and locking the car etc. I removed the fuse as a temp solution, got the car checked out and alarm disabled. Now my car alarm is finicky and the normal "chirp" when locking/unlocking isn't there and is replaced with the horn. Whenever I lock my car I hear "honk --- pause --- honk" and it takes two clicks of the unlock on the fob to unlock the car and sometimes the horn will start blaring doing this. Any ideas? I already changed key fob batteries and will be going to try a different fob and testing the 12V battery. This happened before a couple years ago and eventually the horn stopped working all together. Mechanics did something to the ECU and it fixed. Also, apparently I have an aftermarket alarm system. Car was pre-owned and sold by Toyota.

 

Update: I have also noticed that my dashcam connected to the 12V cigarette lighter was taking several minutes longer to turn on. Could this be due to the P/I fuse being faulty or blown?