One incident? And, it happened when you were trying to help by picking up a former employee's duties (to help the Company)? Come on! This is hard to believe, I don't care how tough the guy is.If there are other incidents (you have alluded to one), they are probably documented in performance reviews/appraisals. On the other hand, if you have gotten good reviews over the years, you may very well have a case against the Company. Don't be afraid to see an attorney. In any case, you should contact the EEOC and discuss the problem.
One last, but very important thought. You are assuming this guy is going to fire you because he asked someone else to ask you to bring in your laptop. Could there be other reasons for bringing in the LT? You may very well think you are getting fired, but nothing is certain until it happens.
Best of luck. If you truly are asked to hit the door, another one will open for you. Treat it as an adventure. What would you like to do with the rest of your life? Something exciting, I hope.
Jim