Not sure if it is a similar problem that TCL RokuTVs experienced with their PlayStation problems.
See if the Onn RokuTV has a HDMI Mode. ( Settings..TV Inputs..HDMI Mode) If it does, select HDMI 2.0 rather than Auto.
Then restart your Playstation and see if it boots up. Apparently from here, you then go to "Sounds and Settings" in the Playstation and select "Video Output Settings" and Enable or set to Automatic the HDR setting.
I don't have an Onn RokuTV so not sure if the HDMI Mode is available as it is not present on my Insignia RokuTV. Additionally, I have read online that you need to verify that you are using a HDMI 2.0 cable.
Feel free to post back with an update. This was an older fix from last year so not sure if still applicable.
