I have a tv. My neighbor lets me use her wi fi, so I get my local news stations, and youtube. I turned the tv off. Ten minutes later it came on by itself, and the top right corner said new device detected. And it showed a rock band. I turned it off. It came back on again, this time another band.
Does your neighbor have kids?
Sounds like someone was trying to cast video to their own TV but connected to yours instead because they are on the same wi-fi network.
I’m a little surprised the TV turned on though but I’m assuming that is just a setting.
No kids. She wouldn’t put on rock music.
My Samsung turns on any time it receives an input.
OP, there’s gonna be a setting for that somewhere on the TV, might have the word “wake” associated with it. There’s also gonna be a setting on whether or not to allow casting or streaming directly to the TV. If that’s not a feature you use, you can turn it off.
Is the wi-fi password protected? Maybe she is sharing with others or the wi-fi isn’t locked down.
Can you share the model? Some so called smart TVs are scary.
Years ago a friend brought his universal tv remote control to a bar. We had a blast, periodically switching channels right when something great was happening in the game, turning the volume way up or down, turning the tv off, then back on when the bartender was just about to touch the on switch.
We never confessed, just stopped doing it when we left.
My next door neighbor plays loud rock music, maybe my tv picked it up. Almost thought I had a ghost.
He isn’t home right now though.
No… can’t tell if joking.
You saw video of a rock band or two right? Someone is connected to the same wi-fi.
Thanks. It was just odd that my tv powered on. The dope solves another question. 
If you do post the model of tv, I’m sure someone will be able to post some explicit instructions to block it if it keeps happening. You might might want to do so no matter what if this wi-fi is as unsecure as I suspect that it is.
Phillips Roku.
You can cast to a Roku device without being on the same network. My neighbours kids sometimes try to cast to mine. They definitely don’t have access to my Wifi.
You might be able to block it
Looking it up, that sounds like “Miracast” which is a wi-fi direct connection. So you are correct. It basically creates it’s own ad-hoc connection without having to be on the same wi-fi network.
My LG TV sometimes has an on-screen message that someone is trying to cast or connect to it and do I want to allow, decline or block the connection attempt. I usually block them (since I live alone and only have a few devices from which I want to connect or cast.
My wife was telling me yesterday that her dad’s TV has turned itself on a few times recently (twice in the middle of the night, once while his hospice care nurse was visiting) and he can’t get it to turn off. We were joking that it was the ghost of her mom, who died last month. Because she loved to watch her TV.
What my wife found upon googling is that some TV remotes will sporadically send out a signal when the batteries are dying, which would explain both the turning on by itself and not being able to turn it off (cuz the batteries are almost dead).
Doesn’t explain the rock bands though…
Yes, I realized afterwords I misspelled it. Goes to library for book on how to spell words properly.
Your house didn’t happen to have been built atop an Indian burial ground, by chance?
No. …