I can't tell exactly what problem you have with this description.
Permanently off to me reads as there is no power to the generator.
However, you may mean that they don't switch from channel OFF to channel ON.
Perhaps they to switch to ON, but in the case of plasma, is not lighting up the tube. Conversely, with remote, not illuminating the remote LEDs.
With that said, there is no real way to give you a solid answer.
Please start with this to see if this addresses the actual nature of your problem. Otherwise we will need much a more detailed description of what you are observing.
For more details, please check the link: