I'm having the same problem. I'm able to turn off the tablet just in time between reboots.
I've tried the factory reset through Settings etc. (i was only succesfull doing it this way once) and tried several times, using the Power and Vol-down button. Did not change anything.
Using Wipe cache data, Wipe User data same story.
Also tried to reinstall the firmware using Odin, also not working.
Does anyone have any other suggestions I could try?