Hi kissmeh89, if you touch the screen for a while, the light of back key\home key\multi task key will turn off. But it doesn't mean they cannot use. You just need to touch it when you need it. According to your description, I have some questions:
1, if the light has turned off, only back key cannot use? or home key and multi task key also cannot use?
2, if the light on, can the back key work?