Green vertical lines across bottom half of Onn TV

Does the TV do that on other things, such as while using a DVD or antenna?  How old is the TV?  You could try unplugging the TV from power for at least a couple of minutes and see if that works or try a factory reset.    It is possible that the TV panel has gone bad or the control board inside has gone bad, which happens pretty frequently with certain budget level TV brands.  Since it is an Onn brand, you should also reach out to Onn technical support.

Hi, Deweyp 

Welcome!

I understand that you've encountered an issue with a Roku TV's screen showing vertical green lines. I'm here to refer you to the right support so you can get help.

For this matter, you may want to contact your Roku TV manufacturer, Onn, and inquire further for assistance. They provide direct support with their TV models.

To contact them, refer to Onn Support

Hope this helps.

Thanks,
Roku Community Team