As the subject line says, My 8 year old KDL46Z5100 starts up with a picture from the Fios STB for about a second, then it goes black, both picture and sound. On a different input (all HDMIs) it still shows Roku main screen etc, BUT when you try and watch anything from Netflix or Amazon Prime, it shows the blue error showing protected content screen but has sound. No DVD picture on the third input, but sound.
I do a power reset, unplugging and replugging it, and it's all back to working fine, but then a couple of days later it starts all over again.
For a while the set has been telling me the time has been lost when I first turn it on, so some battery somewhere is dead, but I've been ignoring that for a couple of years. Could that also be causing the new problem? Am I witnessing the beginning of the end?
You did great in isolating the issue by performing a power reset, but you mentioned you still getting the same issue after a few days. I know the update of your TV is quite old but in case you haven't updated it yet, please perform a software update.