My Roku 2 box won't start. The light is on, flashes and the screen displays "not supported" for just a half a second and then nothing. It was working on this same TV for years and then one night, nothing. Please help.
My opinion, for what it's worth. The box is old, and may have finally died. You even mentioned it had worked for years. Still, I would try a few things first. Try a different HDMI input on the TV, try it on a different TV, try something different in the same HDMI port, try a different HDMI cable. But mainly, if it doesn't work on a different TV, it's probably reached end of life.
Dan Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.