Android 6 update now just keeps cycling startup

[Mark Lem]

AT&T Note 4, been great for last couple years. Phone did the Android 6 update a few days ago, been slow since. Now only boots up to "Samsung Galaxy Note 4 powered by Android" banner, turns off, then cycles again.

I've taken battery out, same thing
I've taken battery out, held power and volume down, wiped the cache, not change.

Am I hosed at this point?

Thanks in advance

 

[Mark Lem]

update:
plugged into charger, it boots up! without charger and only on battery, problem returns. Need new battery