Nothing is going to work unless you can either enter the boot loader or boot into the os.
You should still be able to access hboot unless that is corrupt. At the very least you need to hear the ding on your pc so you know the pc has recognized your device is connected.
Try again with vol up and power, hold until it reboots you should then hear that ding. If not check you have the necessary usb drivers installed on your pc or try a different usb cable.