Welcome to the forum.
There's plenty of people around to help but you'll need to give some more detail on exactly what's wrong. Have a look at the following guide on setting up your box and if you still have problems post back with where it goes wrong and what happens instead
So you don't get any picture on the screen at all? Does the white light appear on the front of the box when it's plugged in? If so, have you tried a different HDMI cable and/or tried connecting to a different HDMI port on your TV?
And you've double checked the TV is set to the right input? (Sorry to ask such a basic question but it's easy to overlook)?
I'd probably try doing a hard reset and seeing if that helps (with the box powered up push a pin into the reset hole at the back and hold it for around 10 seconds then release, see if a picture then appears on the screen). It might also be helpful to try it on a different TV set if you have one in the house.
If that doesn't help, it could well be the box is faulty and needs replacing, but before you do you might want to have a quick word with live chat to see if they can suggest anything to get it going.
To get there go to the following help page
and click the green Contact Us button near the bottom left of it (not the How to Contact Us link right at the bottom as that takes you somewhere else) then choose the Live Chat option on the following page.
You know, there are two (silly) things @Gordon59 has not mentioned:
1) Has he correctly connected the his Now TV box to his modem/router?
2) Has he switched his TV to the HDMI channel? I especially asked this question because, for example, when you connect some devices to a TV the channel switches automatically to that new device, the Now TV box does not auto-switch the TV channels.
My questions may seem daft but it's those little, simple things that can be easily overlooked.
Yep,,you are right, the simple things can often be overlooked,
The OP was asked to check they had selected the right TV input and I'm hoping as they have not posted back that they have either managed to resolve the problem, or that live chat (sometimes it's easier to talk to live chat as, being in real time, they can go through a number of steps quickly rather than having to post on the forum and wait for a reply) have got to the bottom of it for them.
Unfortunately the OP wouldn't have got to the stage of selecting their network connection yet as they had no picture on screen to enable the start of the setup process.
Fingers crossed they are sorted now! 🙂
I cannot fault anything you have said in your post but, after re-reading @Gordon59 posts I can't help feeling something is missing.
However, from a personal point of view, when it comes to "logic" over "feeling" I choose "logic" every time, so I'll push my feelings out of the way and step aside. After all, when dealing with computer kit (or computerised domestics) you have to be logical.