I locked myself out with the engine running, pulled the engine relay to stop the engine, disconnected the battery to keep from running it down, used a Slim Jim to get back in, re-inserted engine relay, reconnected battery, and now the starter does nothing when I turn the key? What's going on? Some security system thing?

 

Did you disconnect the positive or negative side of the battery? Do you have any power or the engine just does not crank?

If no power and you disconnected the positive side of the battery you may have blown the big fuse in the black box that the positive cable goes to (right next to battery).

 

I disconnected the negative side. I have power, but the engine won't crank. Got to be the engine immobilizer. How do I reset it?

 

I was trying to start with just the key - no guts in case! MUST have guts in case to start Mini!!! Had guts out to solder in new battery.