Need to know the TV make/model as well to determine if it's a resolution recognition issue.
Do you see the Roku boot screen when first powered up? Do you see anything (menus, home screen)? Also, Except for players that connect to a USB power source on the TV (like a Stick), your Roku is always powered on. It is waking from sleep mode when you first use it, not powering on.
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.