What version / carrier is the Note 2? What update is it on? What method did you use to root? Is the screen flickering random or whenever you touch something? There's nothing about rooting the phone that would cause an issue like this. At least not on that phone. I'm wondering if you didn't inadvertently click one of the developer options that causes the screen to flash (can't remember the name of it).
Need some help, advice, something fixed? Hit me up on Hangouts @ es0tericcha0s
Now offering unlocking services - including many Sprint phone unlocks! PM for details!
HTC Droid Eris / Motorola Droid / Samsung Galaxy S Fascinate / Motorola Droid X / LG G2x / HTC Evo 3D (x2) / Samsung Epic 4G Touch (Sprint S2) / HTC Amaze / Samsung Galaxy S3 (International) / Samsung Galaxy Note 2 / Nexus 4 / HTC One / Samsung Galaxy S4 / Sony Xperia ZL / Nexus 5 / OnePlus One (64 GB)