Phone stuck in Boot up screen after rooting

[anon(10163482)]

I have (I thought) successfully rooted my Note 4. At least it told me so. On rebooting it sticks in the initial Samsung screen, with flashing blue LED.
The only way to get out of it is to remove the battery.
After doing that, I tried download OS (Power/Home/Vol down) and on selecting Vol up, machine freezes with LGM and "Downloading"

Then tried Recovery mode. Machine went into TWRP screen, and on selecting REboot, the cycle began again, sticking as before. I tried both a cache clear and Factory reset. No change.

Any ideas?

 

[Surasia]

You can flash a custom OS with Odin. Then Close your phone and press volume down , power button and the home button in the same time. Then click on Apply update. Your done