use this twrp https://forum.xda-developers.com/t/...-sm-t560nu-sm-t377p-update-13-4-2016.3302935/Please describe your steps in detail......i have t561 too..... i tried many times.....but getting stuck in viper logo.....
put rom and gapps in a micro sd
backup everything if you want
wipe system,data,internal storage
install rom (i used v5.1)
install gapps nano for arm 7.1
do not install magisk yet
do not install su from twrp (do not swipe for si)
it took about 3 minutes to boot for me.