ZTE Axon 7 Freezing in Daydream

[AC Question]

I was trying out the Google Daydream VR headset with my Axon 7. When I picked Google Photos to use in Daydream my phone suddenly froze and I couldn't get it out of that screen. I've tried all the usual ways to turn the phone off, restart, or to "unfreeze" and it just wouldn't budge. When I had my LG phones I could just take the batteries out but now I can't do that with the built-in battery... What should I do? Has anyone else had similar problems? Thanks!

 

[Guytronic]

If I remember correctly you can hold power+volume down together for about 20 seconds to force the phone into reboot.