do you have to return to home screen from Roku to stop streaming?

I have been out of the house a lot this week. My granddaughter had to have her appendix removed Monday, so I've been helping with babysitting at her house. She is doing great.

I think when I let my grandson shut off the tv the other day, he didn't return from Roku to home before he shut it off. The Roku remote doesn't have a power button. When I checked my broadband usage yesterday, I had used 40%, way more than usual this time of month. I disconnected any device that might have been connected when I noticed, and alerted my provider. I checked this morning and usage had gone down, but still high. I unplugged my cable modem until I can figure out what happened. I'll be on a broadband diet the rest of the month.

I don't have a usage problem if I shut off the tv without leaving Netflix, so I am not sure if Roku caused this. I don't know if I should disconnect and reconnect the Roku stick, or maybe unplug the whole tv to reset everything. I googled some of the terms, but it is so hectic with the kids, I thought I'd get some opinions.

I appreciate any advice.