HTC One M8 Crashed While watching video

[jwzhang23]

hi everyone, i just got my M8 two weeks ago. About 10 minutes ago, I was watching video using the M8 and all of a sudden the screen went blank and what showed up was a digital clock on top and temperature on bottom...and nothing else. the phone is still working because I get notification charm when I receive email. I try hitting the power button, it doesn't do anything. Any one have had similar experience? Thanks!!