When i use the combination for the door the trunk also opens

The most common reason for a central locking to re-open on the lock button is the central locking has detected a door or the trunk isn't closed correctly. Open each door and the trunk to check there is nothing in the latch to 'trip' the unlock setting. Close the doors and trunk and retest the remote.
If this doesn't fix the issue have the wiring to the central locking check ed for loose connections or damaged wiring.

not easy to just disable because it is part of the engine control system and will not start if the security system module is disconnected or tampered with but the most likeley cause is one of the door latches faulty or wiring around the trunk hinge broken/opencircuit the security system thinks a door or the trunk is open. the clue to help is check the dash warning saying door or trunk open when sat inside with ignition on and all doors etc. closed or even the hood switch

Some trunks have a lever near the trunk latch on the lid to disable electrically opening the trunk. Could be a short causing the trunk open switch to open the trunk. If it doesn't open electrically via a button then you have something bent and the trunk doesn't close properly.

Can you open trunk with a key? If so, unplug the electrical for the trunk, till you can fix the problem. Then look up the wiring diagram for trunk release, check wiring circuits, something maybe shorted that connects with your door. I haven't looked to see if bcm has a connection with doors as well as trunk release? The bcm was just a thought may not be relevant?

these are the things that cause beeping ... trunk open, door open any one of your 4 doors not closed properly will cause the beeping, seatbelt chime, lights on or key in ignition when door is openbut check all your doors

OPEN MANUALLY AND CHECK THE STRUTS PS. IF WHEN YOU OPEN IT AND IT GOES BACK DOWN THAT'S YOUR PROBLEM

u have a seperate motor for each door to open them if all work and back doesent see if any wires have come off with it getting slamed a lot or the motor may be goosed hope this helps ivan

most but not all have a back up cable in trunk not sure if yours does or not
more than likely your cable is broke somewhere if you dont have backup in trunk remove trunk trim panel and see if you can find where cable goes to fuel door and pull on it if that doesnt work cut the cable (you be replacing it anyhow) then peel back so u can get at wire inside cable pull on cable (might need pliers) and door should open
if all this fails pry door open with screwdriver

Make sure the drivers door is open and push the button on the drivers door to open trunk. Keep the drivers door open while you open trunk. If you close the drivers door before opening it, it won't open. Well this is what happens to our car. Don't know if it's a fault or the design but this does work for us.

Door Switch May Have Gotten WET thus Causing Corrotion Inside it REPLACE SWITCH with NEW ONE