Stuck in system recovery
Interrupting an Android update is not a good idea as your device is now in an "in between" state that is not usable.  

Most likely you have to flash a complete factory image (also called RUU image) of your device to recover it. 

Usually HTC devices support fastboot, which should allow to flash such an image to your device. Check the HTC ROM Download page for an image matching your specific device.