Chrysler Repair: 1999 300M - Security System problem: wont arm, volt ohm meter, circuit verification

Question
The blinking LED light on the dash has stopped blinking when I lock the car via the key FOB. It was working fine until recently. I had some body work done to the passenger side rear door (my brother backed into it)and (I think) it has not worked since it came out of the shop. I called them and asked if they disconnected it but they said no, there was no reason for them to mess with it at all. The fact that the light no longer blinks leads me to belive that it the system is not working. How do I troubleshoot this problem. FYI-I am very inexperienced in electrical systems. Thanks

Answer
Hi Michael,
You are probably correct that the body experience has something to do with the problem. It probably thinks the door is ajar and therefore won't arm. So check that the door is latched tightly, if necessary move the latch striker. If still no go, then try to arm it while a helper pushes on the door ajar switch in the body at the door.  Other than that, it will require some electrical circuit verification with a volt-ohm meter. But first, check the other doors similarly as this could occur at any door.

Roland