[Q] need help topic

i unlocked bootloader on my nexus 7 2013 and tried to root it following this guide http://nexus7root.com/new-nexus-7-ro...-nexus-7-2013/ im running android 5.0 on it so i used the supersu 2.30 like it said once it started to reboot it got stuck in boot animation ( 4 colored dots swirling) abd i tried wipeing everything i tried reformat i tried factory reset im at a loss please help i have twrp on it and can get into it