Flickering GBC Frontlight
If you install this backlight with the KB installation instructions you will get flickering and no display. This does not mean the KB or HHL lights are faulty, they are just installed differently and both work perfectly well when installed properly. Make sure to use the right solder points as described below. KB install is on the left and HHL install is on the right. Both units are on with full batteries. Move the batteries around on the back and you might get a flicker here and there with the KB install. The video below is an example of the flickering.
This pic is just to show the voltage difference between the DC power input and batteries.