How do I unfreeze my LG X Power phone?

[AC Question]

I plugged my phone in to charge and it went to a Firmware Update screen. Over an hour later it was still at 0%. A small window at the bottom of the screen says "910K B50". I tried to turn it off with the power button on the right side of the phone to no avail. On other phones, I'd pop the battery out for a few seconds to force a reboot, but that's not an option on this phone. Is there another way to reboot this?

 

[B. Diddy]

Welcome to Android Central! Try pressing and holding Power for 10-15 seconds to force a shutdown. Then power on again normally.