I just had the battery changed now the horn is blowing and lights blinking, i do not have keyless entry

Do you have an air bag light lit on the instrument cluster ? Do you have C.C. button's on the steering wheel , do they work ? If the alarm fob (as u call it ) Can make the horns sound , the relay is sending B+ voltage to the horns Don't know how your testing.
System Description
The horn system consists of the following components:
• Horn fuse
• Horn relay
• Horn switch
• Horn(s)
• Body Control Module (BCM)
System Operation
The vehicle horns are activated under the following conditions:
• The horn switch is depressed.
• The body control module (BCM) commands the horns on. The BCM commands the horns on under either of the following conditions:
- When the content theft deterrent system detects a vehicle intrusion. For further information, refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent.
- When the panic button is depressed on the remote control door lock transmitter. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry.
- When the OnStar® system is used to sound the horns, if equipped. For further information, refer to OnStar Description and Operation in Cellular Communications.
- When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry.

Circuit Operation
Battery positive voltage is applied at all times to the horn relay coil and the horn relay switch. Pressing the horn switch applies ground to the horn relay control circuit. The body control module BCM may also apply ground to the horn relay control circuit as described above. When the horn relay control circuit is grounded, the horn relay is energized and battery positive voltage is applied to the horn(s) through the horn control circuit. The horn(s) sound as long as ground is applied to the horn relay control circuit.

The vehicle horns are activated under the following conditions:
?€¢
The horn switch is depressed.

?€¢
The body control module (BCM) commands the horns on. The BCM commands the horns on under either of the following conditions:

-
When the content theft deterrent system detects a vehicle intrusion. For further information, refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent.

-
When the panic button is depressed on the remote control door lock transmitter. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry.

-
When the OnStar?® system is used to sound the horns, if equipped. For further information, refer to OnStar Description and Operation in Cellular Communications.

-
When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information, refer to Keyless Entry System Description and Operation in Keyless Entry

go into the radio and change it there. If they work when it is running then the radio
is where you look

Alarm may have been tripped. Use a keyless entry to unlock the doors.

Horn will sound only after keyless entry system has checked all doors and sensors are in locked condition,
including all doors, hood , truck and other locks. I have copied the sensor locations for you and circuit diagram
for keyless/burglar system. Hope this will help.
Component Location



I’m happy to assist further over the phone at https://www.6ya.com/expert/uttamjeet_2f3adc18600f8ede

Before replacing any Relay. Try disconnecting the negative side of the battery for at least 2-minutes to de-energize the security system, re-setting itself. The reconnect the battery and try your security (and options) system again.
The only other big question that you will have to know: is this a factory installed security system or an aftermarket security system? This makes a difference in security systems, relays etc.

The remote is fine - your problem is the lock actuators in the doors. They're a bit of a pain to replace - so, you may want to have a professional do it.

Press and hold for 2 seconds the LOCK AND UNLOCK buttons on your "keyless entry" keypad. The hazard lights will then blink 3 times and the horn will sound once- you are now good to go.;

Two things that I would look at:

1.) The spark plugs should be changed at this mileage

2.) She may be having the beginnings of an Idle Control Valve ("IAC") failure.

The security LED blinking is normal

The horn issue may be a weak battery on the keyless entry remote transmitter

Its not better to go to a key copying and re-set your remote entry?