here's a link to a forum page with the same issue.
if not helpful just type "random reboot galaxy 12.2" into Google or Yahoo seach, you'll have a tonne of fixes to choose from, all resulting in either version rollback or installing a different root or unrooting
hope this link will be helpful to y'all:
http://www.androidauthority.com/community/threads/samsung-galaxy-note-pro-12-2-reboots-continuously-when-the-battery-drops-below-70.18785/
p.s:
this forum can be very helpful with other issues as well.