It might be a good idea to perform a factory reset on your Now TV stick, here's the URL to the instructions:
So I guess, from your observations, you're Now TV stick is dead, then I have to ask when did you buy it, i.e. is it still within it's 12 month guarantee period? If it is, then you can exchange it for a new one, but if not then you may have to buy yourself a new one.
But before you do anything, if you have another TV try your stick in that one's HDMI port because your original TV's port may be at fault instead of your Now TV stick.
For power on the NowTV Stick are you using the supplied power adapter that came with the Stick or using a 900mA USB port off your television ?
If using the supplied power adapter, see if your television has a 900mA USB port on it and try that with the Stick (500mA USB port will be insufficient, but might show the power light on the stick).
Also if no joy have you a USB 5Vdc Adapter lying around the house (for example some mobile phones and tablets use a USB charger plug) and if so try that with maybe a different USB to micro USB cable has well.
If none of the above works you could still try a factory reset by holding in the reset button on the Stick for about 15 seconds.
Hi again Rebecca
You asked, "Bought it in June how do I get a refund or new one?"
You can either take it back to the retailer you bought it from, along with your receipt, but if you bought it online you will have to contact the online retailer's help desk and get instructions on how to send it back for a refund or replacement.