White screen is a new one. Bad power supply perhaps? Is it a Roku1 or 2?
That's new to me, too. However, after hearing of "green screen", "purple screen", "blue screen" to all describe a failed handshake, I think it is up to the TV to report that the mode or the protection failed, and what color blank screen is up to the manufacturer's discretion.
I asked a few questions that may help isolate what is happening, so hopefully after getting answers to those questions it may become more apparent on what is (or isn't) happening.