@Snoopy74 What model exactly did you get? There are several AV 600 speed models.

Edit: I just saw the "TL-PA4010KIT" in the top part of your post. So you mention wifi and the TV. Did you plug in a network cable from the powerline adapter to the TV? That is not a wifi extender model, it is for wired networking only.

@magarity hi there, thank you so much for your time! I'm rubbish with this sort of thing. 

So , to get the internet in our garage, is this not the right thing? 

@Snoopy74 So let me see if I understand what you've got:

That kit you bought has two little white boxes that plug into the wall mains. One is next to your router in the house, plugged into the wall, and has a network cable from its bottom socket to the router. Right so far?

Then, out at the garage, the second unit is plugged into the wall there.  So it also has a network cable socket on the bottom. Just plug a network cable in there and the other end to the TV. Internet connected TV should have a network plug in the back somewhere. I suspect this cable is the part that has yet to be plugged in? This is all you need to get the TV in the garage to be internet connected. You so have internet in the garage now. It is to the one network socket on the bottom of the TPLink unit there so you can plug in one device, such as the TV, and get internet service on it.

If you want wifi in the garage, for example so that several garage devices can use your home internet then this was the incorrect kit to get. Perhaps whoever advised you misunderstood and thought all you wanted was the TV connected.

TPLink has kits TL-WPA4220 KIT and TL-WPA7510 KIT and TL-WPA8630 KIT that have wifi on the far end from the router if you need more than just the TV connected in the garage.

@Snoopy74 There is usually no need to join a wired network. Just start using the internet features of the TV.  Joining a network is used for wifi because in densely populated areas one should not connect randomly to a neighbor's wifi. But with a wired network, it has to be plugged in on purpose so there is no need to do anything more to join it.

@magarity I think there must be something else wrong. When we try to use internet it says there is no connection.

@Snoopy74 

Did you connect a computer to the cable out in the garage? From the status of the lights and your descriptions, it really does sound like the two powerline units are set up correctly but hooking up a computer would be the final confirmation. Note that you don't have to drag a monitor out to the garage, just use the TV for a computer screen.

You might try asking for help on the TV manufacturer's forum if the computer test shows internet is working in the garage.

@magarity thank you so much for your help, I will try it.