Try enter bios of 5490 and disable touch screen there System Configuration menu
After an unfortunate keyboard accident that resulted in a broken monitor, I am running a second monitor on my son's Inspiron 5490 all-in-one. The touch screen feature is causing the display to flicker due to the damage. I have repeatedly disabled and uninstalled the HID-compliant touch screen, but it reappears every few minutes. Is there any other way to permanently disable the touch screen? 
Inspiron 5490 AIO - Disable Touch Screen Permanently