keyless entry broke after body repair

This is an 2000 Isuzu Trooper that was rear-ended. The body shop had replaced the rear door with surplus parts. I'm guessing it's not an exact year match. So anyways, we got the car but the keyless entry is not working. Pressing LOCK makes it beep indicating a door is still open (probably the rear). The body shop can't figure it out, and we were referred to a alarm install place and they can't figure it out either. The dealer wants $50 to a couple hundred to do diagnostics. Ok, so after that long story, my question is... If I get the bodyshop to agree to pay for another keyless entry, can the factory be turned off and have another one installed?

it looks like the problem is the door pin switch, try to unplug one by one until it doesn't beep, then you have to replace the pin.how own your mind, control your life.

MECP certified. always use a DMM

Thanks for the reply. Sorry to be such a dummy, I'm more of a computer geek than an auto electronics expert :) What would this pin switch look like and is it under the panel of the rear door assembly? I've installed amps and car stereos but no car security/convenience stuff.

the door pin swich are in each door, they should be on the frame of the car not at the door, they are black pin that if you push in the dome light inside the car goes off.how own your mind, control your life.

MECP certified. always use a DMM

Thank you, I found that pin switch and verified that it does turn the dome light on/off. I wonder if there is more than one wire plugged into this switch.

I checked on the pin switch after I got home today and removed the screw that was holding the switch housing. It only has one black wire (with stripe) connected to it and it works as it is supposed to in turning on/off the rear dome light. I did notice one more switch though, although it doesnt look like anything is wired to it. It's about 6 inches from the switch that controls the rear dome but this is mounted on the door and is pushed in by a protruding metal on the body. The part it pushes in is flat plastic on a compression spring. The whole assembly is bolted on the door.