Yes, for switching the modes you need the wire from backlight point of ATARI PCB to pin 4 backlight of LCD mod kit. Otherwise you can't switch between the modes normal picture, scanlines, VGA and VGA scanlines. If you wire pin 1 of LCD mod kit to GND, then VGA modes are not provided and you just have 2 modes: internal 3.5" LCD normal and internal 3.5" with scanlines. You have to switch by BACKLIGHT BUTTON, not thumbwheel. The thumbwheel on LYNX-II is not necessary anymore. It's only necessary on LYNX-I for switching the modes.