I recently bought a Samsung A510FD(Android v5.1.1) and attempted to root it but failed and this messaged appeared on my screen: RECOVERY IS NOT ENFORCING.I was then unable to shut my phone down.By force shutting down my phone with (power off button + volume down button) would cause it to on again.I tried connecting my phone to my computer via USB but my computer wouldn't detect it as well as Odin. Please help me ASAP!
To my experience, the non-SEAndroid enforcement is just a warning, after installing Cyanogenmod on my S4 I had that error every boot, and it still worked.
Try flashing the stock firmware if you cannot get it to boot, perhaps your rooting method is broken.
In case you don't already know, that warning trips one of the warranty bits