supersu binary update failed on 5.0 device.

I've seen one or two threads that were in the same vein as this, but no clear resolution. Every time I open SuperSU, I get the message, "The SU binary needs to be updated. Continue?" I select "Continue," and am given the message to install it normally or through TWRP/CWM. If I try through TWRP, the phone restarts into TWRP, but does nothing. If I select "Normal," I get the "Installation failed!" message. I tried uninstalling/reinstalling SuperSU, but that didn't do anything.
I'm using 5.0 walton device.

SuperSu update

I have SuperSu (zip) installed from recovery.
Can I update it to newer version from APK?

*URGENT* Tablet bricked when installing SuperSU as system app

I have an Acer Iconia One 7 B1-760HD that I just rooted with Kingroot, then useing SuperSU Me I installed SuperSU and replaced Kinguser. When I was looking in the settings I decided to install SuperSU as a system app, because I have multiple accounts on my device, and don't want people to be confused. Once I rebooted, it booted past the "powered by Android" screen, but freezes on the boot animation. I have waited 10 minutes and no boot, tried wiping user data, nothing happened. I really need help with this, as I haven't even had the device 24 hours, and had little to no time for using it.
The system it was running was Lollipop 5.0.1, if that is any use. If anyone has a stock image (.zip) of the /system folder that would be very much appreciated.

(P.S. When running the root integrity check there was 2 files labelled as modified)