Re: Black screen after pressing wrong display type
That support article won't do you much good if you don't have a visible display.
It sounds like you've set your Roku to a display type your tv can't display. Do you have another, higher resolution, tv you can try this Roku on? If it will display for you on that set, go into Settings/Display type, set it to the resolution of the first set, and click "OK, go to [that resolution]". When you get to the countdown screen, click on "Yes, screen looks good" to lock in that resolution. Now return the Roku to the first set and see if the problem is solved.
If you don't have another set to try it on, or if it won't display there either, your best bet may be to do a Factory reset (Settings/System/Advanced system settings/Factory reset) and set it up again from scratch. This will require you to link to your Roku account again and renew your log in to many of your channels.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T