I recently received the neckband, and I finally got to try it out yesterday. Out of the box, it had about 67% battery. I ran through the tutorial and then adjusted the screen settings and linked accounts for about 20 minutes, and then I got into a Netflix series, and after about 25 more minutes of the Netflix series (45 minutes total) the device suddenly powered off.

I booted it back up and noted the battery said 32%, and about 10-15 minutes later, it powered off again, apparently stone-dead. I let it charge in the charging case overnight, and I've just now tried to power it back on, and it took a long time displaying the VITURE flash screen, and then powered off. Again, turned it on and the VITURE flash screen displayed, but quicker, and it just got to the Home screen UI and abruptly powered off again. I noticed these last two times it came on, the fan only came on briefly.

At this point, it doesn't appear to want to even stay on long enough for me to see if there is a firmware update available.

*5-minutes later Edit: Tried booting up 3 more times, and it only displays the VITURE flash screen and then abruptly powers off.