Chosen Solution

My samsung galaxy tab pro 8.4 SM-T320 will mot work without being constantly charging. If not, it will either: -Flash the screen on and off, turn off, restart, and repeat until dead. -Flash screen on and off, and die instantly. I don’t know what to do about it. I have lots of data on it, but I can’t do anything with it because of this.

@frankshooter start off by replacing the battery. A failed battery would exhibit the symptoms you describe. Always do the easy things first. Here is the guide for it Samsung Galaxy Tab Pro 8.4 Battery Replacement