Car will not turn over/electrical problem

I have a Buick LeSabre (2002?) that would not even turn over when I got into the car. However, after turning the key back and forth, I noticed that every now and then the radio would come on. The battery was not dead. Eventually it cranked where I could drive it home. While coming home, I do remember the Security light being on. When I tried to crank it again (this morning), it kept making a sound and the radio light was almost flickering and occasionally the radio lights would be full force and on. The lights would fade and become strong and at other times would not even come on. It would usually come on if I turned the key backwards. However, I could not get it to even click or lights to even come on in the car (aside from the occasional flicker) turning the key forwards. The dashboard lights would not come on and a couple of times when the gauges started to work/come on, I was able to hear a click when trying to crank it but it still would not turn over. Please help!