I thought I have found an alternative way to power on my Nintendo DS Lite by simultaneously pressing the L, R and X button without using the side Power Button slide switch. After doing some thorough investigation, it turns out that I was wrong.
The Power Button has been cranky for about 4 months now. There was a time when the DS will power itself on without anyone touching it - and it can even turn itself off sometimes. This morning, I found out that I could trigger the DS to power itself on/off by just pressing down hard on the X button. And if I have used the slide switch, and everything is just in the right orientation somewhere in the DS, a gentle push on the X button is all it needs.
Still, this is an option that I could use when the power slide switch is not responsive.