Are you holding reset in for over 15 seconds, while power is being fed to the Stick?
Have you tested that the power supply is switched on at the mains and supplying power?
You can try it on any other device you have with a suitable socket for the plug on the end of the mains connector.
Set a Payment PIN on your account so that no-one but you can buy memberships on it. Check your bank accounts monthly for any other unexpected payments to Now. That way you can at least nip them in the bud, while you and Now figure out whose fault they are.