Ribs burned to a crisp following directions. What does "medium high" mean?
Ribs should not be cooked with direct heat, generally. The directions on the meat are VERY defective. You should turn the left burner on, and put the ribs in the right side of the grill. You should cook at a temperature between 250-300F, typically for 4-5 hours. They're done when the meat pulls back from the bone and when you can easily tear the meat between bones, not when they hit a certain temperature. 

Check out amazingribs.com, and also get your money back. The instructions on the packaging border on fraud.