XPS One 2710 -- Touch Screen NOT working at all

My touch screen is not available on my 2710.  It worked fine for a very long time.

Calibration is not available...System->About says "No pen or touch input is available for this display."

I noticed after I upgraded to Windows 10.   (but that's not necessarily the precise time is dropped out, as I don't use it a lot)

I then downgraded back to 8.   Not there.   Figured that I might as well go back to Windows 10.

I did other things within same rough period of time.   BIOS upgraded to A12.   Changed out some drivers, etc.

I've tried drivers, checked the touch cable connection on the motherboard...but haven't made a single step forward.

Would love to hear some suggestions or ideas.

Thanks in advance.

Rick