2003 Chevy Malibu acting strange, electrically speaking!?

[bkstgzillgod]

Sometimes the door chimes with no key in the ignition or lights on.
Horn beeps 5 seconds after starting and after turning off again sometimes. Is there something wrong with the battery, it's been in 2+ years, unknown when it was bought. recently had to jump start it.
Reset the computer a couple days ago, now what?

 

[Bubba B]

If you had to jump start it, then it's time to get a new battery.