When you finally find that booster switch pull it off the wall and make sure the connections there are correct - and tight.
You didn't say what happens with the BR TV when you try to use it. I assume it works OK?
Sometimes you have such a weak signal that multiple TVs can be used. It's rare - but it happens. So maybe see if the LR TV works on a different station when the BR is on????
2018 F350, 2019 Grand Design 310GKR