its not the phone its the root (its not perm root) for perm root you need a rooted kernel like the one Dmrlook has posted for stock filesystems that is a perm rooted kernel
no, It's not a temp root. This root, if done right, is a permanent root that I couldn't get rid of no matter what I did. For several days afterwards, I tried restoring it to the backup I made with CWM before rooting it and I tried deleting "su" via multiple methods. Nothing worked. The su binary refused to go away. No clue why it doesn't work for you, but i took a stock samsung replenish, did the exact steps I put in the guide, and turned it into a rooted device that had stock EVERYTHING, but with 1 tiny binary in it that allowed me to get root whenever I wanted via superuser.apk or the Android Debug Bridge.