When scanned, the QR code says "x+y+r". Press all 3 buttons at once.
Also, do you have a New3DS? If so, you can watch the video in the next room in the web browser. Otherwise, continue scrolling down.
The video takes a year to finally say what to do. It says press Up, then Down, then A, then Y. Now you can finally get to the underwhelming ending!
