iPhone 5 or earlier Iphone 3g touch doesn't work with a good screen

[vdivon]

So, I got an Iphone 3g has a problem. When I turn it on, the touch screen does not work. I changed the screen but still nothing. Can it be a system problem??

 

[Mactech20]

Possibly, The 3G has a the digitizer and LCD separate. Did you replace the digitizer or the LCD?