I picked up a 96 Nissan sentra GLE, never got any remotes with it.
Worked fine for about a week then Somehow the alarm got armed, horn beeps won't start.

Anyone know how to disable it manually without having a remote?

I only have a plain metal key, not sure if these had chipped keys or not.

I have tried unlocking the doors and trunk with the key, no luck.

I have looked for an aftermarket alarm in the car under the dash and such but can't locate one so I think it is factory.

Any help appreciated