HTC ONE hung and can not restart the phone
As per XDA here you can perform force restart by doing this.

To reboot the phone without ADB, just hold down the Vol Up and power button for 9 seconds, the phone should shut down.


If this doesn't power down the phone, you can try this. Lot of people has reported success in this method for most of the HTC phones.

Put your phone under a bright light then hold power+volume down. 


If both of them fails, you have to wait till the battery die and let it charge and power on the phone normally.

Hope this helps you. Good luck.