Others have complained that this is also a problem with the Ellipisis 8 and the 7 as well. The tablet just shuts down and requires holding in the power button and the volume-down button for 20 seconds to restart, followed by an additional 2 minutes for the reboot process.
It can happen in the middle of watching a movie or streaming a podcast. After restarting, the podcast I was listening to restarted from the beginning, not from where it was interrupted.
Though the problem is most frustrating when it interrupts a streaming event, it is also frustrating when I simply turn off the screen for a while and then come back 20 minutes later to turn it back on and find I have to reboot. The problem occurs regardless of the battery's power level.