In attempting to keep from getting bumped off the airplay at school, the technology department told me to add a lock to the passcode so no one else could be on the apple tv or air play in my classroom. While attempting to plug in a number for the code-I was automatically assigned on and the screen went blank before I could write down the number. How do I retrieve this number or do I have to start all over with my iPad? I know to turn off the lock but I need to be able to lock my apple tv so no one else in the building is piggybacking off my airplay.