Help getting started with Roku devices, including setup, connecting your device to your TV, linking a Roku device to your account at my.roku.com/link, adding channels, subscribing to services, and more.
Note that if you have an Express device then you will just be directed right back here. Also, if your device gets its power from a USB cable make sure you're using the supplied adapter and not the TV's USB port.
Some have reported success in getting beyond the update step of new installations by connecting to a different network (a wifi hotspot on a cell phone or a friend's wifi). Once it has completed the update and starts to function, you can then change the network connection to your intended home network via Settings > Network > Set up connection.
This hasn't worked for everyone, but enough have reported success that it's probably worth a try.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T