DS Lite touchscreen not working at all

Hello, I just bought 2 new DS Lite's, each came neatly in it's sealed factory box with 2 pairs of screen protectors, each one was a little over 50 dollars. After I got them, and used them for about 3 days, a couple of hours each day, the touchscreen stopped working completely, I have only used them for GBA games. I have searched online for solutions but to no avail. The calibrate your screen feature doesnt help, the touchscreen doesn't work at all. And the same thing happened to both systems. The weird thing is that while using the "calibrate" option, the mark will move when I press the DS in the area between the Y button and the START button.