Old compnay computer

A good while ago I was laid off after a company restructuring. They were meant to send me a box to return the company computer, as I am remote, but so far no box has come. I'm 90% sure they have forgotten about me. However, the computer has been off since my firing and I worry about simply turning it on and acting as if its now my computer....

So what are my options? Is this 'instantly tracks your location and sends the theft police' an actual worry? How can I make this computer safely mine, regardless?