head unit touch screen calibration menu missing

10.2" Secain Chinese head unit touch screen only works with a usb mouse.Since I reinstalled and updated the iGo navigation app last year, I noted that touch sensitivity reduced and eventually became nonexistent. I notice that the touch screen calibration option has dissapeared from settings and every effort including 'Factory Reset' failed to recover the menu option or to get the touch reactivated. Further confusion with trying to update the Android version due to the unit showing that it is 'V 5.0.1' and a test app identifying it as 'V 4.4.2 KitKat'. I would very much appreciate any guidance as to any action that I should take to get the touch working again and maybe recover the menu option. [![Unit specs[![\]\[1\]]]]