See if re pairing the remote again works.
If no joy and you own a smartphone, what happens if you download the free Roku Remote App from your phones App Store.
Does the Roku App respond to the stick ?
Unfortunately the app doesn’t seem to work either as it needs to be synced to the same network but haven’t managed to get that far with the stick yet.
the remote is flashing green, but doesn’t none of the button on the remote work once I get to the “choose your network” section in the set up.
If you own a smartphone, try using the phone has a wifi hotspot with the stick (temporarily).
Should the stick connect to the phone via hotspot, let it go through the software update, then try connecting to your Router again.
Sounds to me there is either a conflict between your Router and NowTV stick or the stick is located in a poor wifi reception where it is currently located.
Before taking the stick back, i would try a full factory reset on your Router (not soft reboot) see your Router instructions on how to set it back to default.
If that doesn't work, have you got another TV anywhere around the home, just to temporary hook up the stick to see if the stick will pick up and accept your home wifi network.
Should none of the above work then i have run out of ideas, apart from testing the stick out on somebody else's home network such has a close family member, friend or neighbour etc.
Other than that, try a different stick or if practically possible look at a now tv smart box over Ethernet.
Sometimes having the Router in close proximity to a WiFi device is not the ideal situation.
What i would be also inclined to try, is to go into the NowTV Hub Router settings by using an internet browser and type in the url address bar 192.168.0.1 and once the Hub Router page shows click on the wireless tab, then when asked for username and password use admin & nowtv.
Then go into both the 2.4ghz and 5ghz wifi bands and rename the SSID name on both frequencies so they are more easily identified (i just add 2.4G & 5G onto the end of my own SSID network names on my NowTV Hub).
Then go into the stick Network system settings or another factory stick reset and try picking 5G on your home network first to see if it accepts that or if not try the 2.4G.
This is a bit of a long short but worth a try before taking the stick over to your parents house to test out on their Router.