Is the outside tv plugged in? The outlet is directly behind the tv and a little hard to reach. Assume you have 110 volt power when trying—either shore power or generator? On my trailer I can use the remote for the inside tv to control the outside tv so try that too.
The tv does not need to be on for the speakers to work as they can play sound from the inside stereo.
You do not need to turn on the amplifier for the antenna to get it to turn on but it will likely improve the picture.
2018 Voltage 3305