Usually when you get an ALL WHITE SCREEN or one with Vertical lines on the screen, that usually points to a Dead TCON board.
A quick test to try....Activate the TV's menu or the volume bar or any onscreen displays.
If you don't see them appear on your TV, it's telling us the TCON is blocking that signal from appearing on the TV screen.
If they DO APPEAR, then the TCON is ok, and then the main board is creating the white picture and the purple lines, but that's not something I see the main board do.
So, check your TV's Menu...that separates the two boards and tells us what is going on.
Look on the right side of your TV set. Sony usually places a sticker on the right for wall mount TVs. The model number should be there. Sony models always start with the letter K on about 99% of their TV sets. Only the newer internet/smart Tv models are using the NSX prefix on their models.
KDL , KDF, KF....that's what we usually see start the TV's model number.