One of the things I love about the internet is that when you have a problem with something (a drone, a computer, a car, whatever) you can be assured that somebody, somewhere has probably had the same problem and may have a solution. That premise has helped me learn and fix things that would have been near impossible otherwise.
That being said, the sheer number of Spark users at your disposal virtually ensures that you can find the solution to your problem. It may end up with having to send the drone back to DJI if there's something seriously wrong, but most of the time the kind of issues you're having can be corrected. Give a good, accurate description of the problem in a post and the knowledgeable folks here can guide you to the answer. It can be frustrating and too often, DJI's list of most common issues may not be your exact problem, but give it a try. You may be amazed at how good this little drone can be once your problems are ironed out. Btw, a search of these forums will show the QR code thing has never worked from the beginning, but there's another way to register and the answer is a few keystrokes away. Good luck!