I took my 2000 Cherokee to get an inspection on Friday. It passed, I got it home, drove a little bit around town and then I had to go give my girlfriend's Pontiac a jump. On saturday morning, my Jeep wouldn't start--battery completely dead. I thought maybe one of the battery cables was loose, so I reconnected them to the terminals and noticed that the running lights were stuck on. After charging the battery with another vehicle, I started it right up.

When I cam back later on Saturday, I went to start the Jeep again and it was completely dead. This time, I noticed that as soon as I put the key in the ignition the running lights came on and then they wouldn't go off. I tried jumping my Cherokee again and it didn't work--running lights were still on but not start. I then saw something kind of shoved up under the dash. It turns out it was a plastic oval shaped box with a port that accepts an electrical plug and on it it said "sensor" with a little adjustable screw. I have never seen this before and it certainly was never just sitting there like that...

Now, I know the truck once had an alarm system, but when I bought it I was told that it wasn't hooked up anymore. My father thinks that when they were inspecting the truck they must have disturbed something with the alarm system or broke that sensor box off and that's causing the truck to not start. I'm going to call the mechanic first thing tomorrow, but I have a feeling he's going to give me a hard time and say it's not his fault... Any suggestions?