Screen flickers when I turn on but screen remains black can only see when I put a flash light up to it
I'm assuming this is a Roku TV, thal is, a TV with Roku capability built in, rather than a separate Roku streaming device connected to a TV.
Roku only supplies the operating system for a "Roku TV". This sounds like a hardware issue that needs to be referred to the manufacturer of the set.
Roku TV Manufacturer Support Contacts:
https://community.roku.com/t5/Manufacturer-Support-Warranty-Resources/Contacting-Support-for-Your-Ro...