ROKU Express comes up. When you select a program to watch, screen becomes black but audio works. Googled the problem, and it said to do a factory reset of the ROKU. After that, it works until you turn off TV and back on again. Then same thing happens. Any ideas?.
Your problem may have been caused by a recent update to your router which affects some Roku models. If you received this update it changed the router's wifi connection parameters from b/g/n to g/n. This has been reported lately with equipment from Comcast/Xfinity and Cox, but there may be others.
Affected users report the Roku identifies the local network as available and rates the connection quality, but will not then connect. The fix is to switch the router configuration protocols from the g/n wifi that was set by the update back to b/g/n. If you don't have access to your router's configuration controls you may have to have your internet provider do it for you.
Step-by-step post from @AvsGunnar for Comcast/Xfinity users:
https://community.roku.com/t5/Network-Wireless-Wired-Connections/Error-014-30-stuck-for-three-days/m...