Welcome and thank you for posting here in the Roku Community, @aleaaa!
We appreciate you reaching out for support and we'd be happy to help you contact the right support for this.
It seems like this might be a power issue. In this case, I highly recommend reaching out to your TV manufacturer for additional support.
You may reach them here: Hisense Support
Best regards,
Carly
Carly Y.
Roku Community Moderator