Security system won't activate
 

I just bought a 2001 Honda Accord EX. I had to replace the radiator and fix a rear door handle. Before I did that the security system (as shown on the driver door LED) activated once I closed and locked the door. Now it does not. The dashboard doesn't show any door or trunk open, so I must assume the mechanic either 1. didn't attach the sensor properly that shows the rear door is locked, 2. the hood latch is not showing closed (it was sticking when I bought the car and had to be slammed), or 3. he deactivated the system to work on it and didn't reactivate it (he has since quit). How do I narrow down the issue and re-activate my security system?

Since the hood latch switch is a common "issue" area I would start my testing there.