I'm sorry. I assumed 'beat it into parts' was hyperbole. Just what exactly are you planning on using to beat it into parts? Assuming the hard drive is reasonably secured you aren't going to be 'long gone' by the time security shows up. You're still going to be smashing it trying to get at the hard drive when they show up. Sure, you know what a hard drive looks like, but in which of the battleship grey 1/4" tempered steel boxes is it in? Going to grab them all? Well, if I were to design the system I would probably have a lot of that stuff attached together with some pretty thick and heavy duty cable, the kind you use to keep people from stealing stuff, so you're going to have to haul a significant portion of the 300 lbs robot with you and then hope it doesn't have any sort of lo-jack system.
And incidentally, while you are doing all of this you are still in a parking garage being monitored by other cameras. How are you getting it out of there? Loading it up in your truck? Would that be the one that had its license plate visible when you drove into the garage? And that's the same one you plan on using to drive out of the garage after the alert goes off? Gee. I wonder where the human guards should go to head you off.
This isn't meant to be a statement of 'it's impossible! You will never do it!' I am sure all of these hurdles can eventually be surmounted. What it is meant to be is a statement of 'that's probably more work than you're thinking'.
Remember, to each and every complex problem there is inevitably a simple and easy answer, and it is usually wrong.