android bootloop after flashing supersu
Samsung is notorious for boot loops.  

You are having problems with the system integrity check that's run by the kernel.  

You need to install System-less root, Magisk uses systemless root however I'm a SuperSU fan and I hate magisk.  

You just need to install the correct systemless root zip.  

I have a SuperSU installer for Android 5.1.1,
SuperSU v2.82 Systemless

For some strange reason, I was able to enable full root access after installing the systemless zip.  

To enable the full root like I did, you need TWRP 3.2+  


Open TWRP and install SuperSU with TWRP 
( Install full root using TWRP ) 
Do not reboot yet, Install the systemless root zip, it will automatically change to " system root mode " and install root access bypassing the systemless install.  
after literally 10 minutes boot time, my device boots with full root access.