I am a user of Dell Inspiron 7567 bought 3 months ago. After 1 month of use I am getting a black patch on top left corner of screen (image attached). It was pretty small earlier, but it has grown bigger now. I ran scree diagnostics through Dell Support application. The colour generation of the rest of screen is perfect except that black patch.
Apologies that your computer is not working as you expected. You may wish to contact Tech Support for additional troubleshooting. You can contact Tech Support at 1-800-624-9896 or 1-800-288-4410, or you can initiate a chat session http://dell.to/2v4snVm