Thanks for reaching out to the community. I am sorry to hear that you are experiencing a power issue with your Noise Cancelling Headphones 700.
Are you attempting to turn on your headphones whilst they are charging connected to your computer? If so, this is normal as you can not use the Noise Cancelling Headphones 700 whilst they are charging.
If not,does the LED illuminate at all on your headset?
Please let us know, we would love to get this resolved for you.